Amphiphilic polysiloxane prepolymers and uses thereof

ABSTRACT

The present invention provides an amphiphilic polysiloxane prepolymer which comprises hydrophilic monomeric units derived from at least one hydrophilic vinylic monomer, polysiloxane crosslinking units derived from at least one polysiloxane crosslinker having at least two terminal ethylenically-unsaturated groups, dangling polysiloxane chains each of which is terminated with one ethylenically unsaturated group, and chain-transfer units derived from a chain transfer agent other than a RAFT agent. A prepolymer of the invention is suitable for making hydrogel contact lenses. The present invention is also related to hydrogel contact lenses made from an amphiphilic polysiloxane prepolymer of the invention and to processes for preparing an amphiphilic polysiloxane prepolymer of the invention and for making silicone hydrogel contact lenses.

This application is a continuation of application Ser. No. 14/014,631filed Aug. 30, 2013, now U.S. Pat. No. 8,987,403, which is acontinuation of application Ser. No. 13/193,642 filed Jul. 29, 2011, nowU.S. Pat. No. 8,557,940, which claims the benefits under 35 USC §119 (e)of U.S. provisional application No. 61/369,109 filed Jul. 30, 2010,incorporated by reference in its entirety.

The present invention is related to a class of amphiphilic polysiloxaneprepolymers suitable for making hydrogel contact lenses. The presentinvention is also related to hydrogel contact lenses made from anamphiphilic polysiloxane prepolymer of the invention and to processesfor preparing an amphiphilic polysiloxane prepolymer of the inventionand for making silicone hydrogel contact lenses.

BACKGROUND

Currently, commercially available silicone hydrogel contact lenses areproduced according to a conventional cast molding technique involvinguse of disposable plastic molds and a mixture of monomers in thepresence or absence of macromers. However, disposable plastic moldsinherently have unavoidable dimensional variations, because, duringinjection-molding of plastic molds, fluctuations in the dimensions ofmolds can occur as a result of fluctuations in the production process(temperatures, pressures, material properties), and also because theresultant molds may undergo non-uniformly shrinking after the injectionmolding. These dimensional changes in the mold may lead to fluctuationsin the parameters of contact lenses to be produced (peak refractiveindex, diameter, basic curve, central thickness etc.) and to a lowfidelity in duplicating complex lens design.

Such disadvantages encountered in a conventional cast-molding techniquecan be overcome by using the so-called Lightstream Technology™ (CIBAVision), as illustrated in U.S. Pat. Nos. 5,508,317, 5,789,464,5,849,810, and 6,800,225, which are incorporated by reference in theirentireties. The Lightstream Technology™ involves reusable molds producedin high precision and curing under a spatial limitation of actinicradiation (e.g., UV). Lenses produced according to the LightstreamTechnology™ can have high consistency and high fidelity to the originallens design, because of use of reusable, high precision molds. Inaddition, contact lenses with high quality can be produced at relativelylower cost due to the short curing time and a high production yield.

In order to apply the Lightstream Technology™ in making siliconehydrogel contact lenses, silicone-containing prepolymers have beendeveloped, as described in U.S. Pat. Nos. 6,039,913, 6,043,328,7,091,283, 7,268,189 and 7,238,750, 7,521,519; commonly-owned US patentapplication publication Nos. US 2008-0015315 A1, US 2008-0143958 A1, US2008-0143003 A1, US 2008-0234457 A1, US 2008-0231798 A1, andcommonly-owned U.S. patent application Ser. Nos. 12/313,546, 12/616,166and 12/616,169, which are incorporated by reference in their entireties.However, those types of prepolymers disclosed in the above patents andpatent applications may have some practical limitations in their use formaking silicone hydrogel contact lenses according to LightstreamTechnology™.

A commonly-owned copending U.S. patent application Ser. No. 12/456,364(herein incorporated by reference in its entirety) discloses a methodfor making silicone hydrogel contact lenses from a monomer mixture(i.e., a lens-forming composition) according to the LightstreamTechnology™. However, it is discovered here that in addition torelatively longer curing time, relatively significant shrinkage duringcuring of the monomer mixture in molds can occur that may greatly impedethe application of the Lightstream Technology™ in the manufacturing ofsilicone hydrogel contact lenses.

Therefore, there is still a need for new prepolymers suitable for makingsislicone hydrogel contact lenses according to the LightstreamTechnology™.

SUMMARY OF THE INVENTION

The invention provides an amphiphilic branched polysiloxane prepolymersuitable for making silicone hydrogel contact lenses according to theLightstream Technology™. The polysiloxane prepolymer compriseshydrophilic monomeric units derived from at least one hydrophilicvinylic monomer, polysiloxane crosslinking units derived from at leastone polysiloxane crosslinker having at least two terminalethylenically-unsaturated groups, dangling polysiloxane chains each ofwhich is terminated with one ethylenically unsaturated group, andchain-transfer units derived from a chain transfer agent other than aRAFT agent.

The invention also provides a method for making silicone hydrogelcontact lenses. The method comprises the steps of: (i) obtaining anamphiphilic branched polysiloxane prepolymer of the invention (asdescribed above), (ii) using the amphiphilic branched polysiloxaneprepolymer to prepare a lens-forming composition which further comprisesa free-radical initiator and optionally at least one polymerizablecomponent selected from the group consisting of a hydrophilic vinylicmonomer, a silicone-containing vinylic monomer or macromer, ahydrophobic vinylic monomer, a linear polysiloxane crosslinkerterminated with two ethylenically-unsaturated groups, a crosslinkingagent having a molecular weight of less than 700 Daltons, and mixturesthereof; (ii) introducing the lens-forming composition into a mold,wherein the mold has a first mold half with a first molding surfacedefining the anterior surface of a contact lens and a second mold halfwith a second molding surface defining the posterior surface of thecontact lens, wherein said first and second mold halves are configuredto receive each other such that a cavity for receiving the lens-formingmaterial is formed between said first and second molding surfaces; and(iii) polymerizing the lens-forming material in the cavity to form asilicone hydrogel contact lens.

The invention further provides a method for producing an amphiphilic,branched polysiloxane prepolymer of the invention.

The invention also further provides a silicone hydrogel contact lenscomprising a polymeric material obtained from polymerization of alens-forming composition comprising an amphiphilic branched polysiloxaneprepolymer of the invention.

These and other aspects of the invention will become apparent from thefollowing description of the presently preferred embodiments. Thedetailed description is merely illustrative of the invention and doesnot limit the scope of the invention, which is defined by the appendedclaims and equivalents thereof. As would be obvious to one skilled inthe art, many variations and modifications of the invention may beeffected without departing from the spirit and scope of the novelconcepts of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Generally, the nomenclatureused herein and the laboratory procedures are well known and commonlyemployed in the art. Conventional methods are used for these procedures,such as those provided in the art and various general references. Wherea term is provided in the singular, the inventors also contemplate theplural of that term. The nomenclature used herein and the laboratoryprocedures described below are those well known and commonly employed inthe art.

“Contact Lens” refers to a structure that can be placed on or within awearer's eye. A contact lens can correct, improve, or alter a user'seyesight, but that need not be the case. A “silicone hydrogel contactlens” refers to a contact lens comprising a silicone hydrogel material.

A “hydrogel” or “hydrogel material” refers to a polymeric material whichcan absorb at least 10 percent by weight of water when it is fullyhydrated.

A “silicone hydrogel” refers to a silicone-containing hydrogel obtainedby copolymerization of a polymerizable composition comprising at leastone silicone-containing vinylic monomer or macromer, asilicone-containing crosslinker, and/or at least one crosslinkablesilicone-containing prepolymer.

A “vinylic monomer” refers to a low molecular weight compound that hasone sole ethylenically-unsaturated group. Low molecular weight typicallymeans average molecular weights less than 700 Daltons.

A “vinylic macromer” refers to a medium and high molecular weightcompound which comprises one sole ethylenically unsaturated groups.Medium and high molecular weight typically means average molecularweights greater than 700 Daltons.

The term “olefinically unsaturated group” or “ethylenically unsaturatedgroup” is employed herein in a broad sense and is intended to encompassany groups containing at least one >C═C< group. Exemplary ethylenicallyunsaturated groups include without limitation (meth)acryloyl

allyl, vinyl

styrenyl, or other C═C containing groups.

As used herein, “actinically” in reference to curing, crosslinking orpolymerizing of a polymerizable composition, a prepolymer or a materialmeans that the curing (e.g., crosslinked and/or polymerized) isperformed by actinic irradiation, such as, for example, UV/visibleirradiation, ionizing radiation (e.g. gamma ray or X-ray irradiation),microwave irradiation, and the like. Thermal curing or actinic curingmethods are well-known to a person skilled in the art.

The term “(meth)acrylamide” refers to methacrylamide and/or acrylamide.

The term “(meth)acrylate” refers to methacrylate and/or acrylate.

A “hydrophilic vinylic monomer”, as used herein, refers to a vinylicmonomer which can be polymerized to form a homopolymer that iswater-soluble or can absorb at least 10 percent by weight of water.

A “hydrophobic vinylic monomer” refers to a vinylic monomer which can bepolymerized to form a homopolymer that is insoluble in water and canabsorb less than 10 percent by weight of water.

As used herein, the term “amino group” refers to a functional group of—NHR′ in which R′ is hydrogen or a C₁-C₂₀ unsubstituted or substituted,linear or branched alkyl group.

As used herein, the term “azlactone group” refers to a functional grouphaving the formula of

in which r is 0 or 1; R₁ and R₂ independently can be an alkyl grouphaving 1 to 14 carbon atoms, a cycloalkyl group having 3 to 14 carbonatoms, an aryl group having 5 to 12 ring atoms, an arenyl group having 6to 26 carbon and 0 to 3 sulfur, nitrogen and/or oxygen atoms, or R₁ andR₂ taken together with the carbon to which they are joined can form acarbocyclic ring containing 4 to 12 ring atoms.

As used herein “polysiloxane” refers to a compound or a segmentincluding at least one divalent radical of

in which R₃, R₄, R₅, R₆, R₇, R₈, R₉, and R₁₀, independently of oneanother, are C₁-C₁₀ alkyl, C₁-C₁₀ aminoalkyl, C₁-C₁₀ hydroxyalkyl,C₁-C₁₀ ether, C₁-C₄ alkyl- or C₁-C₄-alkoxy-substituted phenyl, C₁-C₁₀fluoroalkyl, C₁-C₁₀ fluoroether, C₆-C₁₈ aryl radical,cyano(C₁-C₁₂-alkyl), -alk-(OCH₂CH₂)_(n)—OR₁₁, in which alk is C₁-C₆alkylene divalent radical, R₁₁ is hydrogen or C₁-C₆ alkyl, and n is aninteger of from 1 to 10; m and p independently of each other are aninteger of from 0 to 350 and (m+p) is from 1 to 700.

A “crosslinker” refers to a compound having at least twoethylenically-unsaturated groups.

A “crosslinking agent” refers to a compound with two or moreethylenically unsaturated groups and with molecular weight less than 700Daltons. Crosslinking agents may be used to improve structural integrityand mechanical strength. The amount of a cross-linking agent used isexpressed in the weight content with respect to the total polymer and ispreferably in the range from about 0.05% to about 4%, and morepreferably in the range from about 0.1% to about 2%. Examples ofpreferred cross-linking agents include without limitationtetraethyleneglycol di-(meth)acrylate, triethyleneglycoldi-(meth)acrylate, ethyleneglycol di-(meth)acrylate, diethyleneglycoldi-(meth)acrylate, trimethylopropane trimethacrylate, pentaerythritoltetramethacrylate, bisphenol A di methacrylate, vinyl methacrylate,allyl(meth)acrylate, ethylenediamine di(meth)acrylamide, glyceroldimethacrylate, N,N′-methylenebis(meth)acrylamide,N,N′-ethylenebis(meth)acrylamide, N,N′-dihydroxyethylenebis(meth)acrylamide, triallyl isocyanurate, triallyl cyanurate,allyl(meth)acrylate,1,3-bis(methacrylamidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,1,3-bis(N-(meth)acrylamidopropyl)-1,1,3,3-tetrakis-(trimethylsiloxy)disiloxane,1,3-bis(methacrylamidobutyl)-1,1,3,3-tetrakis(trimethylsiloxy)-disiloxane,1,3-bis(methacryloxyethylureidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,and combinations thereof. A more preferred cross-linking agent is ahydrophilic crosslinking agent, such as, tetra(ethyleneglycol)diacrylate, tri(ethyleneglycol) diacrylate, ethyleneglycol diacrylate,di(ethyleneglycol) diacrylate, glycerol dimethacrylate, N,N′-methylenebis(meth)acrylamide, N,N′-ethylene bis(meth)acrylamide,N,N′-dihydroxyethylene bis(meth)acrylamide, triallyl isocyanurate,triallyl cyanurate, or combination thereof.

The term “fluid” as used herein indicates that a material is capable offlowing like a liquid.

A “prepolymer” refers to a starting polymer which contains two or moreethylenically unsaturated groups and can be cured (e.g., crosslinked orpolymerized) actinically to obtain a crosslinked polymer having amolecular weight much higher than the starting polymer.

A “silicone-containing prepolymer” refers to a prepolymer which containssilicone.

“Molecular weight” of a polymeric material (including monomeric ormacromeric materials), as used herein, refers to the weight-averagemolecular weight unless otherwise specifically noted or unless testingconditions indicate otherwise.

“Polymer” means a material formed by polymerizing one or more monomers.

The term “RAFT” refers to radical addition-fragmentation transfer orreversible addition fragmentation chain transfer, as understood by aperson skilled in the art.

A “RAFT agent” refers to a dithioester compound of

in which R_(L) is a leaving group and has its traditional meanings asunderstood by one skilled in the art; R_(Z) is an activating group andhas its traditional meanings as understood by one skilled in the art.

As used herein, the term “ethylenically functionalized” in reference toa copolymer or a compound is intended to describe that one or moreethylenically groups have been covalently attached to a copolymer orcompound through the pendant or terminal reactive functional groups ofthe copolymer or the compound according to a coupling process.

An “ethylenically functionalizing vinylic monomer” refers to a vinylicmonomer having one reactive functional group capable of participating ina coupling (or crosslinking) reaction known to a person skilled in theart.

A “coupling reaction” is intended to describe any reaction between apair of matching functional groups in the presence or absence of acoupling agent to form covalent bonds or linkages under various reactionconditions well known to a person skilled in the art, such as, forexample, oxidation-reduction conditions, dehydration condensationconditions, addition conditions, substitution (or displacement)conditions, Diels-Alder reaction conditions, cationic crosslinkingconditions, ring-opening conditions, epoxy hardening conditions, andcombinations thereof.

Non-limiting examples of coupling reactions under various reactionconditions between a pair of matching co-reactive functional groupsselected from the group preferably consisting of amino group (—NHR′ asdefined above), hydroxyl group, carboxylic acid group, acid halidegroups (—COX, X=Cl, Br, or I), acid anhydrate group, aldehyde group,azlactone group, isocyanate group, epoxy group, aziridine group, thiolgroup, and amide groups (—CONH₂), are given below for illustrativepurposes. An amino group reacts with aldehyde group to form a Schiffbase which may further be reduced; an amino group —NHR′ reacts with anacid chloride or bromide group or with an acid anhydride group to forman amide linkage (—CO—NR′—); an amino group —NHR′ reacts with anisocyanate group to form a urea linkage (—NR′—C(O)—NH—); an amino group—NHR′ reacts with an epoxy or aziridine group to form an amine bond(C—NR′); an amino group reacts (ring-opening) with an azlactone group toform a linkage (—C(O)NH—CR₁R₂—(CH₂)_(r)—C(O)—NR′—); an amino group —NHR′reacts with a carboxylic acid group in the presence of a couplingagent—carbodiimide (e.g., 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide(EDC), N,N′-dicyclohexylcarbodiimide (DCC),1-cylcohexyl-3-(2-morpholinoethyl)carbodiimide, diisopropylcarbodiimide, or mixtures thereof) to form an amide linkage; a hydroxylreacts with an isocyanate to form a urethane linkage; a hydroxyl reactswith an epoxy or aziridine to form an ether linkage (—O—); a hydroxylreacts with an acid chloride or bromide group or with an acid anhydridegroup to form an ester linkage; an hydroxyl group reacts with anazlactone group in the presence of a catalyst to form a linkage(—C(O)NH—CR₁R₂—(CH₂)_(r)—C(O)—O—); a carboxyl group reacts with an epoxygroup to form an ester bond; a thiol group (—SH) reacts with anisocyanate to form a thiocarbamate linkage (—N—C(O)—S—); a thiol groupreacts with an epoxy or aziridine to form a thioether linkage (—S—); athiol group reacts with an acid chloride or bromide group or with anacid anhydride group to form a thiolester linkage; a thiol group groupreacts with an azlactone group in the presence of a catalyst to form alinkage (—C(O)NH-alkylene-C(O)—S—); a thiol group reacts with a vinylgroup based on thiol-ene reaction under thiol-ene reaction conditions toform a thioether linkage (—S—); and a thiol group reacts with anacryloyl or methacryloyl group based on Michael Addition underappropriate reaction conditions to form a thioether linkage.

It is also understood that coupling agents with two reactive functionalgroups may be used in the coupling reactions. For example, adiisocyanate, di-acid halide, di-carboxylic acid, di-azlactone, ordi-epoxy compound can be used in the coupling of two hydroxyl, two aminogroups, two carboxyl groups, two epoxy groups, or combination thereof; adiamine or dihydroxyl compound can be used in the coupling of twoisocyanate, two epoxy, two aziridine, two carboxyl, two acid halide, ortwo azlactone groups, or combinations thereof.

The reactions conditions for the above described coupling reactions aretaught in textbooks and are well known to a person skilled in the art.

As used herein, the term “partially ethylenically-functionalizedpolysiloxane” means a mixture of products obtained as a result of anethylenically functionalizing reaction between an ethylenicallyfunctionalizing vinylic monomer having one first reactive functionalgroup and a functional polysiloxane compound having two or more secondreactive functional groups at a molar equivalent ratio,

$R_{Equivalent}\left( {{i.e.},\frac{\left\lbrack {{functionalizing}\mspace{14mu}{vinylic}\mspace{14mu}{monomer}} \right\rbrack_{eq}}{\left\lbrack {{linear}\mspace{14mu}{polysiloxane}\mspace{14mu}{compound}} \right\rbrack_{eq}}} \right)$of about 0.95 (or 95%) or less, wherein one first reactive functionalgroup can react with one second reactive functional group in thepresence or absence of a coupling agent according to a known couplingreaction as discussed later to form a covalent linkage. As used herein,the term “xx % ethylenically-functionalized polysiloxane” means amixture of products obtained in which the ratio of the ethylenicallyfunctionalizing vinylic monomer and a functional polysiloxane compoundat a molar equivalent ratio, R_(Equivalent), of “xx %” (i.e., a valuefrom about 40% to about 97%, preferably from about 50% to about 95%,more preferably from about 60% to about 92%, even more preferably fromabout 70% to about 90%).

As an illustrative example, if a functional polysiloxane compound to beethylenically functionalized is a linear polysiloxane compound havingtwo terminal reactive functional groups and the molar equivalent ratioR_(Equivalent) of an ethylenically-functionalizing vinylic monomer tothe polysiloxane compound is about 80%, then a 80%ethylenically-functionalized polysiloxane is a mixture of (a) a linearpolysiloxane crosslinker having two terminal ethylenically unsaturatedgroups, (b) a polysiloxane vinylic monomer or macromer terminated withone ethylenically-unsaturated group and one second reactive functionalgroup, and (c) unreacted linear polysiloxane compound terminated withtwo second reactive functional groups. The percentages of components(a)-(c) of the 80% ethylenically-functionalized polysiloxane (aftersubstantial completion of reaction) can be estimated according to thefollowing formula:[Component(a)]%=R _(Equivalent) ×R _(Equivalent)=64%[Component(b)]%=2×R _(Equivalent)×(1−R _(Equivalent))=32%[Component(c)]%=(1−R _(Equivalent))×(1−R _(Equivalent))=4%

It should be understood that a polysiloxane compound to be ethylenicallyfunctionalized can be a star compound having “n” (e.g., 3 to 5)polyslioxane arms each terminated with one reactive functional groupcapable of participating a coupling reaction. The number ofethylenically-functionalizing reaction products in the resultant mixturewould be (n+1) and their percentages are respectively,(R_(Equivalent))^(n), (R_(Equivalent))^(n−1)×(1−R_(Equivalent))×n,(R_(Equivalent))^(n−2)×(1−R_(Equivalent))²×n,(R_(Equivalent))×(1−R_(Equivalent))^(n−1)×n, (1−R_(Equivalent))^(n).

As used herein, the term “multiple” refers to two or more.

A free radical initiator can be either a photoinitiator or a thermalinitiator. A “photoinitiator” refers to a chemical that initiates freeradical crosslinking/polymerizing reaction by the use of light. Suitablephotoinitiators include, without limitation, benzoin methyl ether,diethoxyacetophenone, a benzoylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, Darocure® types of photoinitiators, and Irgacure® typesof photoinitiators, preferably Darocure® 1173, and Irgacure® 2959.Examples of benzoylphosphine oxide initiators include2,4,6-trimethylbenzoyldiphenylophosphine oxide (TPO);bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; andbis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. Reactivephotoinitiators which can be incorporated, for example, into a macromeror can be used as a special monomer are also suitable. Examples ofreactive photoinitiators are those disclosed in EP 632 329, hereinincorporated by reference in its entirety. The polymerization can thenbe triggered off by actinic radiation, for example light, in particularUV light of a suitable wavelength. The spectral requirements can becontrolled accordingly, if appropriate, by addition of suitablephotosensitizers.

A “thermal initiator” refers to a chemical that initiates radicalcrosslinking/polymerizing reaction by the use of heat energy. Examplesof suitable thermal initiators include, but are not limited to,2,2′-azobis(2,4-dimethylpentanenitrile),2,2′-azobis(2-methylpropanenitrile), 2,2′-azobis(2-methylbutanenitrile),peroxides such as benzoyl peroxide, and the like. Preferably, thethermal initiator is 2,2′-azobis(isobutyronitrile) (AlBN).

A “polymerizable UV-absorbing agent” refers to a compound comprising anethylenically-unsaturated group and a UV-absorbing moiety or a latentUV-absorbing moiety.

A “UV-absorbing moiety” refers to an organic functional group which canabsorb or screen out UV radiation in the range from 200 nm to 400 nm asunderstood by a person skilled in the art.

A “polymerizable latent UV-absorbing agent” refers to a compoundcomprising an ethylencially unsaturated group and a UV-absorbing moietywhich has been protected by a labile function group so that itsabsorption coefficients of UV radiation in the wavelength region from200 nm to 400 nm are about 50% or less, preferably 70% or less, morepreferably about 90% or less of those of the UV-absorbing moiety withoutthe protected labile function group.

The term “labile functional group” means a protective functional groupwhich can be removed (cleaved) from another functional group beingprotected by the labile functional group.

A “spatial limitation of actinic radiation” refers to an act or processin which energy radiation in the form of rays is directed by, forexample, a mask or screen or combinations thereof, to impinge, in aspatially restricted manner, onto an area having a well definedperipheral boundary. A spatial limitation of UV/visible radiation isobtained by using a mask or screen having a radiation (e.g., UV/visible)permeable region, a radiation (e.g., UV/visible) impermeable regionsurrounding the radiation-permeable region, and a projection contourwhich is the boundary between the radiation-impermeable andradiation-permeable regions, as schematically illustrated in thedrawings of U.S. Pat. No. 6,800,225 (FIGS. 1-11), and U.S. Pat. No.6,627,124 (FIGS. 1-9), U.S. Pat. No. 7,384,590 (FIGS. 1-6), and U.S.Pat. No. 7,387,759 (FIGS. 1-6), all of which are incorporated byreference in their entireties. The mask or screen allows to spatiallyprojects a beam of radiation (e.g., UV/visible radiation) having across-sectional profile defined by the projection contour of the mask orscreen. The projected beam of radiation (e.g., UV/visible radiation)limits radiation (e.g., UV/visible radiation) impinging on alens-forming material located in the path of the projected beam from thefirst molding surface to the second molding surface of a mold. Theresultant contact lens comprises an anterior surface defined by thefirst molding surface, an opposite posterior surface defined by thesecond molding surface, and a lens edge defined by the sectional profileof the projected UV/visible beam (i.e., a spatial limitation ofradiation). The radiation used for the crosslinking is radiation energy,especially UV/visible radiation, gamma radiation, electron radiation orthermal radiation, the radiation energy preferably being in the form ofa substantially parallel beam in order on the one hand to achieve goodrestriction and on the other hand efficient use of the energy.

In the conventional cast-molding process, the first and second moldingsurfaces of a mold are pressed against each other to form acircumferential contact line which defines the edge of a result contactlens. Because the close contact of the molding surfaces can damage theoptical quality of the molding surfaces, the mold cannot be reused. Incontrast, in the Lightstream Technology™, the edge of a resultantcontact lens is not defined by the contact of the molding surfaces of amold, but instead by a spatial limitation of radiation. Without anycontact between the molding surfaces of a mold, the mold can be usedrepeatedly to produce high quality contact lenses with highreproducibility.

The term “dangling polysiloxane chains” in reference to an amphiphilicbranched polysioloxane copolymer or prepolymer is intended to describethat the copolymer or prepolymer comprises linear polysiloxane chainseach of which comprises one or more polysiloxane segments and isanchored to the main chain of the copolymer or prepolymer through onesingle covalent linkage at one of the two ends of the polysiloxanechain.

“Dye” means a substance that is soluble in a lens-forming fluid materialand that is used to impart color. Dyes are typically translucent andabsorb but do not scatter light.

A “pigment” means a powdered substance (particles) that is suspended ina lens-forming composition in which it is insoluble.

“Surface modification” or “surface treatment”, as used herein, meansthat an article has been treated in a surface treatment process (or asurface modification process) prior to or posterior to the formation ofthe article, in which (1) a coating is applied to the surface of thearticle, (2) chemical species are adsorbed onto the surface of thearticle, (3) the chemical nature (e.g., electrostatic charge) ofchemical groups on the surface of the article are altered, or (4) thesurface properties of the article are otherwise modified. Exemplarysurface treatment processes include, but are not limited to, a surfacetreatment by energy (e.g., a plasma, a static electrical charge,irradiation, or other energy source), chemical treatments, the graftingof hydrophilic vinylic monomers or macromers onto the surface of anarticle, mold-transfer coating process disclosed in U.S. Pat. No.6,719,929 (herein incorporated by reference in its entirety), theincorporation of wetting agents into a lens formulation for makingcontact lenses proposed in U.S. Pat. Nos. 6,367,929 and 6,822,016(herein incorporated by references in their entireties), reinforcedmold-transfer coating disclosed in U.S. Patent Application No.60/811,949 (herein incorporated by reference in its entirety), and ahydrophilic coating composed of covalent attachment or physicaldeposition of one or more layers of one or more hydrophilic polymer ontothe surface of a contact lens.

“Post-curing surface treatment”, in reference to a silicone hydrogelmaterial or a soft contact lens, means a surface treatment process thatis performed after the formation (curing) of the hydrogel material orthe soft contact lens in a mold.

A “hydrophilic surface” in reference to a silicone hydrogel material ora contact lens means that the silicone hydrogel material or the contactlens has a surface hydrophilicity characterized by having an averagedwater contact angle of about 90 degrees or less, preferably about 80degrees or less, more preferably about 70 degrees or less, morepreferably about 60 degrees or less.

An “average contact angle” refers to a water contact angle (anglemeasured by Sessile Drop), which is obtained by averaging measurementsof at least 3 individual contact lenses.

An “antimicrobial agent”, as used herein, refers to a chemical that iscapable of decreasing or eliminating or inhibiting the growth ofmicroorganisms such as that term is known in the art. Preferred examplesof antimicrobial agent include without limitation silver salts, silvercomplexes, silver nanoparticles, silver-containing zeolites, and thelikes

“Silver nanoparticles” refer to particles which are made essentially ofsilver metal and have a size of less than 1 micrometer.

The intrinsic “oxygen permeability”, Dk, of a material is the rate atwhich oxygen will pass through a material. In accordance with theinvention, the term “oxygen permeability (Dk)” in reference to a contactlens means an apparent oxygen permeability which is measured with asample (film or lens) having an average thickness over the area beingmeasured according to a known method. Oxygen permeability isconventionally expressed in units of barrers, where “barrer” is definedas [(cm³ oxygen)(mm)/(cm²)(sec)(mm Hg)]×10⁻¹⁰.

The “oxygen transmissibility”, Dk/t, of a lens or material is the rateat which oxygen will pass through a specific lens or material with anaverage thickness of t [in units of mm] over the area being measured.Oxygen transmissibility is conventionally expressed in units ofbarrers/mm, where “barrers/mm” is defined as [(cm³ oxygen)/(cm²)(sec)(mmHg)]×10⁻⁹.

The “ion permeability” through a lens correlates with the IonofluxDiffusion Coefficient. The Ionoflux Diffusion Coefficient, D (in unitsof [mm²/min]), is determined by applying Fick's law as follows:D=−n′/(A×dc/dx)where n′=rate of ion transport [mol/min]; A=area of lens exposed [mm²];dc=concentration difference [mol/L]; dx=thickness of lens [mm].

In general, the invention is directed to a class of amphiphilic branchedpolysiloxane prepolymer of the invention, a method for making anamphiphilic branched polysiloxane prepolymer of the invention, a methodfor making silicone hydrogel contact lenses from a prepolymer of theinvention, and silicone hydrogel contact lenses prepared from aprepolymer of the invention.

In the first aspect, the invention provides an amphiphilic branchedpolysiloxane prepolymer suitable for making silicone hydrogel contactlenses according to the Lightstream Technology™. The polysiloxaneprepolymer of the invention comprises (1) from about 5% to about 75%,preferably from about 10% to about 65%, more preferably from about 15%to about 55%, even more preferably from about 20% to about 45%, byweight of hydrophilic monomeric units derived from at least onehydrophilic vinylic monomer, (2) from about 1% to about 85%, preferablyfrom about 2.5% to about 75%, more preferably from about 5% to about65%, by weight of polysiloxane crosslinking units derived from at leastone polysiloxane crosslinker having two or more terminalethylenically-unsaturated groups, (3) from about 2% to about 48%,preferably from about 3% to about 38%, more preferably from from about4% to about 28%, by weight of dangling polysiloxane chains each of whichis terminated with an ethylenically unsaturated group, and (4) fromabout 0.25% to about 5%, preferably from about 0.5% to about 4%, morepreferably from about 0.75% to about 3%, even more preferably from about1% to about 2%, by weight of chain-transfer units derived from a chaintransfer agent other than a RAFT agent.

In accordance with the invention, an amphiphilic branched polysiloxaneprepolymer is soluble in a solvent or a mixture of two or more solventsat room temperature so that a lens-forming composition containing fromabout 5% to about 90% by weight of the amphiphilic branched polysiloxaneprepolymer can be obtained.

Example of suitable solvents includes without limitation, water,tetrahydrofuran, tripropylene glycol methyl ether, dipropylene glycolmethyl ether, ethylene glycol n-butyl ether, ketones (e.g., acetone,methyl ethyl ketone, etc.), diethylene glycol n-butyl ether, diethyleneglycol methyl ether, ethylene glycol phenyl ether, propylene glycolmethyl ether, propylene glycol methyl ether acetate, dipropylene glycolmethyl ether acetate, propylene glycol n-propyl ether, dipropyleneglycol n-propyl ether, tripropylene glycol n-butyl ether, propyleneglycol n-butyl ether, dipropylene glycol n-butyl ether, tripropyleneglycol n-butyl ether, propylene glycol phenyl ether dipropylene glycoldimethyl ether, polyethylene glycols, polypropylene glycols, ethylacetate, butyl acetate, amyl acetate, methyl lactate, ethyl lactate,i-propyl lactate, methylene chloride, 2-butanol, 1-propanol, 2-propanol,menthol, cyclohexanol, cyclopentanol and exonorborneol, 2-pentanol,3-pentanol, 2-hexanol, 3-hexanol, 3-methyl-2-butanol, 2-heptanol,2-octanol, 2-nonanol, 2-decanol, 3-octanol, norborneol, tert-butanol,tert-amyl, alcohol, 2-methyl-2-pentanol, 2,3-dimethyl-2-butanol,3-methyl-3-pentanol, 1-methylcyclohexanol, 2-methyl-2-hexanol,3,7-dimethyl-3-octanol, 1-chloro-2-methyl-2-propanol,2-methyl-2-heptanol, 2-methyl-2-octanol, 2-2-methyl-2-nonanol,2-methyl-2-decanol, 3-methyl-3-hexanol, 3-methyl-3-heptanol,4-methyl-4-heptanol, 3-methyl-3-octanol, 4-methyl-4-octanol,3-methyl-3-nonanol, 4-methyl-4-nonanol, 3-methyl-3-octanol,3-ethyl-3-hexanol, 3-methyl-3-heptanol, 4-ethyl-4-heptanol,4-propyl-4-heptanol, 4-isopropyl-4-heptanol, 2,4-dimethyl-2-pentanol,1-methylcyclopentanol, 1-ethylcyclopentanol, 1-ethylcyclopentanol,3-hydroxy-3-methyl-1-butene, 4-hydroxy-4-methyl-1-cyclopentanol,2-phenyl-2-propanol, 2-methoxy-2-methyl-2-propanol2,3,4-trimethyl-3-pentanol, 3,7-dimethyl-3-octanol, 2-phenyl-2-butanol,2-methyl-1-phenyl-2-propanol and 3-ethyl-3-pentanol,1-ethoxy-2-propanol, 1-methyl-2-propanol, t-amyl alcohol, isopropanol,1-methyl-2-pyrrolidone, N,N-dimethylpropionamide, dimethyl formamide,dimethyl acetamide, dimethyl propionamide, N-methyl pyrrolidinone, andmixtures thereof.

An amphiphilic branched polysiloxane prepolymer of the invention isobtained by: (i) polymerizing a polymerizable composition to obtain anamphiphilic branched polysiloxane copolymer, wherein the polymerizablecomposition comprises (a) a partially ethylenically-functionalizedpolysiloxane, wherein the partially ethylenically-functionalizedpolysiloxane is a mixture of reaction products obtained by reacting afirst ethylenically functionalizing vinylic monomer having a firstreactive functional group with a functional polysiloxane compound havingtwo or more second reactive functional groups at a molar equivalentratio, R_(Equivalent), of from about 40% to about 95%, preferably fromabout 50% to about 95%, more preferably from about 60% to about 92%,even more preferably from about 70% to about 90% (the ethylenicallyfunctionalizing vinylic monomer to the functional polysiloxanecompound), wherein each first reactive functional group reacts with onesecond reactive functional group in the presence or absence of acoupling agent to form a covalent bond or linkage, wherein the mixtureof reaction product comprises at least one polysiloxane crosslinkershaving at least two ethylenically unsaturated groups and at least onepolysiloxane vinylic monomer or macromer having at least one secondreactive functional group and at least one ethylenically unsaturatedgroup; (b) at least one hydrophilic vinylic monomer; (c) optionally, butpreferably, a hydrophobic vinylic monomer, more preferably, a bulkyhydrophobic vinylic monomer (i.e., one having a bulky substitute group;(d) a chain transfer agent other than a RAFT agent, wherein the chaintransfer agent optionally but preferably including a third reactivefunctional group; and (e) a free-radical initiator (a photoinitiator orthermal initiator, preferably a thermal initiator); and (ii)ethylenically functionalizing the amphiphilic branched polysiloxanecopolymer by reacting it with a second ethylenically functionalizingvinylic monomer having a fourth reactive functional group which reactswith one second or third reactive functional group in the presence orabsence of a coupling agent to form a covalent linkage, thereby formingthe amphiphilic branched polysiloxane prepolymer.

Preferably, the functional polysiloxane compound in the polymerizablecomposition is defined by formula (1) or (2)FG-G₁-PDMS-G₂-FG  (1)CR(-G₁-PDMS-G₂-FG)_(a1)  (2)in which

-   -   G₁ and G₂ independent of each other is a direct bond, a linear        or branched C₁-C₁₀ alkylene divalent radical, a divalent radical        of

-   -    in which q is an integer of from 1 to 5 and alk and alk′        independent of each other are a C₁-C₆ alkylene divalent radical,        or a divalent radical of -R′₁-X₁-E-X₂-R′₂- in which R′₁ and R′₂        independent of each other is a direct bond, a linear or branched        C₁-C₁₀ alkylene divalent radical, or a divalent radical of

-   -    as defined above, X₁ and X₂ independent of each other are a        linkage selected from the group consisting of

-   -    in which R′ is H or C₁-C₈ alkyl, E is an alkyl diradical, a        cycloalkyl diradical, an alkylcycloalkyl diradical, an alkylaryl        diradical, or an aryl diradical with up to 40 carbon atoms which        may have ether, thio, or amine linkages in the main chain;    -   PDMS is a polysiloxane divalent radical of formula (3)

-   -   -   in which ν is 0 or 1, ω is an integer of from 0 to 5, U₁ and            U₂ independent of each other represent a divalent radical of            —R′₁—X₁-E-X₂—R′₂— as defined above or a divalent radical of

-   -   -    as defined above, D₁, D₂ and D₃ independently of each other            are a divalent radical selected from the group consisting of            —(CH₂CH₂O)_(t)—CH₂CH₂— in which t is an integer of 3 to 40,            —CF₂—(OCF₂)_(a)—(OCF₂CF₂)_(b)—OCF₂— in which a and b            independent of each other is an integer of 0 to 10 provided            that a+b is a number in the range of 10 to 30, and a            divalent group of formula (4)

-   -   -    in which R₃, R₄, R₅, R₆, R₇, R₈, R₉, and R₁₀, independently            of one another, are C₁-C₁₀ alkyl, C₁-C₁₀ aminoalkyl, C₁-C₁₀            hydroxyalkyl, C₁-C₁₀ ether, C₁-C₄ alkyl- or            C₁₋₄-alkoxy-substituted phenyl, C₁-C₁₀ fluoroalkyl, C₁-C₁₀            fluoroether, C₆-C₁₈ aryl radical, cyano(C₁-C₁₂-alkyl),            -alk-(OCH₂CH₂)_(n)—OR_(ii), in which alk is C₁-C₆ alkylene            divalent radical, R₁₁ is hydrogen or C₁-C₆ alkyl, and n is            an integer of from 1 to 10; m and p independently of each            other are an integer of from 0 to 350 and (m+p) is from 1 to            700, provided that at least one of D₁, D₂ and D₃ is            represented by formula (3);

    -   CR is a multivalent organic radical having a valence of a1;

    -   a1 is an integer of 3, 4 or 5; and

    -   FG is selected from the group consisting of amino group (—NHR as        defined above), hydroxyl group, carboxylic acid group, acid        halide groups (—COX, X=Cl, Br, or I), acid anhydrate group,        aldehyde group, azlactone group, isocyanate group, epoxy group,        aziridine group, thiol (—SH), and amide groups (—CONH₂).

Preferably, in formula (1) or (2), PDMS is a polysiloxane divalentradical of formula (3) in which: ν is 0 or 1, preferably 1, ω is aninteger of from 0 to 3, preferably 1, U₁ and U₂ are as defined above,D₁, D₂ and D₃ independently of each other are a divalent radical offormula (4) in which R₃ to R₁₀ independent of one another are methylgroups, fluoro(C₁-C₁₈-alkyl), and/or -alk-(OCH₂CH₂)_(n)—OR₁₁ in whichalk is C₁-C₆-alkylene divalent radical and R₁₁ is C₁-C₆ alkyl, and n isan integer from 1 to 10, m and p independently of each other are aninteger of from 1 to 698 and (m+p) is from 2 to 700.

Various difunctional group (reactive) terminated polysiloxanes (i.e.,having one sole polysiloxane segment of formula (4)) can be obtainedfrom commercial suppliers (e.g., from Gelest, Inc, or Fluorochem).Otherwise, one skilled in the art will know how to prepare suchdifunctional group-terminated polysiloxanes according to proceduresknown in the art and described in Journal of Polymer Science—Chemistry,33, 1773 (1995) (herein incorporated by reference in its entirety).

Where a functional polysiloxane compound of formula (1) is a functionalchain-extended polysiloxane compound, namely having two to fivepolysiloxane segments of formula (4), such functional chain-extendedpolysiloxane compound can be prepared by reacting a difunctional group(reactive)-terminated polysiloxane compound having one sole polysiloxanesegment of formula (4) and two third reactive functional groups with acoupling agent having two fourth reactive functional groups, wherein thethird and fourth reactive functional groups are different from eachother but reactive with each other and are selected from the groupconsisting of amino group (—NHR as defined above), hydroxyl group, thiolgroup, carboxylic acid group, acid halide groups (—COX, X=Cl, Br, or I),acid anhydrate group, aldehyde group, azlactone group, isocyanate group,epoxy group, aziridine group, thiol (—SH), and amide groups (—CONH₂). Acoupling agent having two fourth reactive functional groups can be adiisocyanate, a di-acid halide, a di-carboxylic acid compound, a di-acidhalide compound, a di-azlactone compound, a di-epoxy compound, adiamine, or a diol. A person skilled in the art knows well to select acoupling reaction (e.g., anyone described above in this application) andconditions thereof to prepare a functional chain-extended polysiloxanecompound.

Any suitable C₄-C₂₄ diisocyanates can be used in the invention. Examplesof preferred diisocyanates include without limitation isophoronediisocyanate, hexamethyl-1,6-diisocyanate, 4,4′-dicyclohexylmethanediisocyanate, toluene diisocyanate, 4,4′-diphenyl diisocyanate,4,4′-diphenylmethane diisocyanate, p-phenylene diisocyanate,1,4-phenylene 4,4′-diphenyl diisocyanate, 1,3-bis-(4,4′-isocyantomethyl) cyclohexane, cyclohexane diisocyanate, and combinations thereof.

Any suitable diamines can be used in the invention. An organic diaminecan be a linear or branched C₂-C₂₄ aliphatic diamine, a C₅-C₂₄cycloaliphatic or aliphatic-cycloaliphatic diamine, or a C₆-C₂₄ aromaticor alkyl-aromatic diamine. A preferred organic diamine isN,N′-bis(hydroxyethyl)ethylenediamine, N,N′-dimethylethylenediamine,ethylenediamine, N,N′-dimethyl-1,3-propanediamine,N,N′-diethyl-1,3-propanediamine, propane-1,3-diamine,butane-1,4-diamine, pentane-1,5-diamine, hexamethylenediamine, andisophorone diamine.

Any suitable diacid halides can be used in the invention. Examples ofpreferred diacid halide include without limitations fumaryl chloride,suberoyl chloride, succinyl chloride, phthaloyl chloride, isophthaloylchloride, terephthaloyl chloride, sebacoyl chloride, adipoyl chloride,trimethyladipoyl chloride, azelaoyl chloride, dodecanedioic acidchloride, succinic chloride, glutaric chloride, oxalyl chloride, anddimer acid chloride.

Any suitable di-epoxy compounds can be used in the invention. Examplesof preferred di-epoxy compounds are neopentyl glycol diglycidyl ether,1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether,glycerol diglycidyl ether, ethylene glycol diglycidyl ether, diethyleneglycol diglycidyl ether, polyethylene glycol diglycidyl ether, propyleneglycol diglycidyl ether, and dipropylene glycol diglycidyl ether. Suchdi-epoxy compounds are available commercially (e.g., those DENACOLseries di-epoxy compounds from Nagase ChemteX Corporation).

Any suitable C₂-C₂₄ diols (i.e., compounds with two hydroxyl groups) canbe used in the invention. Examples of preferred diols include withoutlimitation ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol, polyethylene glycol, propylene glycol,1,4-butanediol, various pentanediols, various hexanediols, and variouscyclohexanediols.

Any suitable C₃-C₂₄ di-carboxylic acid compounds can be used in theinvention. Examples of preferred di-carboxylic acid compounds includewithout limitation a linear or branched C₃-C₂₄ aliphatic dicarboxylicacid, a C₅-C₂₄ cycloaliphatic or aliphatic-cycloaliphatic dicarboxylicacid, a C₆-C₂₄ aromatic or araliphatic dicarboxylic acid, or adicarboxylic acid which contains amino or imido groups or N-heterocyclicrings. Examples of suitable aliphatic dicarboxylic acids are: oxalicacid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelicacid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid,dodecanedioic acid, dimethylmalonic acid, octadecylsuccinic acid,trimethyladipic acid, and dimeric acids (dimerisation products ofunsaturated aliphatic carboxylic acids, such as oleic acid). Examples ofsuitable cycloaliphatic dicarboxylic acids are:1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid,1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and1,4-dicarboxylmethylcyclohexane, 4,4′-dicyclohexyldicarboxylic acid.Examples of suitable aromatic dicarboxylic acids are: terephthalic acid,isophthalic acid, o-phthalic acid, 1,3-, 1,4-, 2,6- or2,7-naphthalenedicarboxylic acids, 4,4′-diphenyldicarboxylic acid,4,4′-diphenylsulphone-dicarboxylic acid,1,1,3-trimethyl-5-carboxyl-3-(p-carboxyphenyl)-indane, 4,4′-diphenylether-dicarboxylic acid, bis-p-(carboxylphenyl)-methane.

Any suitable C₁₀-C₂₄ di-azlactone compounds can be used in theinvention. Examples of such diazlactone compounds are those described inU.S. Pat. No. 4,485,236 (herein incorporated by reference in itsentirety).

Any suitable dithiols can be used in the invention. Examples of suchdithiols include without limitations C₂-C₁₂ alkyl dimercaptans (e.g.,ethyl dimercaptan, propyl dimercaptan, butyl dimercaptan, pentamethylendimercaptan, hexamethylene dimercaptan, heptamethylene dimercaptan,octamethylen dimercaptan, nonamethylene dimercaptan, decamethylenedimercaptan, or combinations thereof), ethylcyclohexyl dimercaptan,dipentene dimercaptan, benzenedithiol, methyl-substitutedbenzenedithiol, benzenedimethanethiol, glycol dimercaptoacetate, ethylether dimercaptan (diglycol dimercaptan), triglycol dimercaptan,tetraglycol dimercaptan, dimercaprol, dimercaptopropanol,dimercaptobutanol, dimercaptopentanol, dimercaptopropionic acid,dihydrolipoic acid, dithiothreitol, dimercaptosuccinic acid, andcombinations thereof.

In formula (2), CR is the core of the functional multi-arm starpolysiloxane and is derived from a branching agent, namely a compoundshaving 3 to 5, preferably 3, fifth reactive functional groups which canparticipate in any known coupling reaction and are selected from thegroup consisting of amine groups, hydroxyl groups, carboxylic groups,isocyanate groups, thiol groups, (meth)acryloyl groups, vinyl groups(i.e., in which each carbon-carbon double bond is not directly connectedto a carbonyl group or to oxygen or nitrogen atom), acid halide groups,epoxy groups, and combinations thereof. Examples of preferred branchingagents include without limitation glycerol, diglycerol, triglycerol,arabitol, 1,1,1-trishydroxymethylethane, 1,1,1-trishydroxymethylpropane,1,2,4-butanetriol, 1,2,6-hexanetriol, erythritol, pentaerythritol,diethylenetriamine, N-2′-aminoethyl-1,3-propylenediamine,N,N-bis(3-aminopropyl)-amine, N,N-bis(6-aminohexyl)amine,triethylenetetramine, the isocyanurate trimer of hexamethylenediisocyanate, 2,4,6-toluene triisocyanate, p, p′, p″-triphenylmethanetriisocyanate, and the trifunctional trimer (isocyanurate) of isophoronediisocyanate, trimesoyl chloride, cyclohexane-1,3,5-tricarbonylchloride, trimer acid chloride, triglycidylisocyanurate (TGIC),trimethylopropane trimethacrylate, pentaerythritol tetramethacrylate,triallyl isocyanurate, triallyl cyanurate, aconitic acid, citric acid,1,3,5-cyclohexanetricarboxylic acid,1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid, 1,2,3 benzenetricarboxylic acid, 1,2,4 benzene tricarboxylic acid,1,3,5-pentanetrithiol.

A person skilled in the art knows well how to prepare a functionalmulti-arm star polysiloxane of formula (2) according to any knowncoupling reactions. For example, a polysiloxane of formula (2) can beprepared as follows, A branching agent is reacted with an excess molarequivalent amount of a di-functionalized polydisiloxane to form afunctional multi-arm star polydisiloxane with three or four arms eachhaving a terminal reactive functional group for further reactions,according to any known coupling reactions including those describedabove. If each arm comprises more than one polysiloxane segments, afunctional chain-extended polysiloxane prepared above can be used toreact with a branching agent.

In accordance with the invention, any suitableethylenically-functionalizing vinylic monomers can be used in theinvention for preparing partially ethylenically-functionalizedpolysiloxanes and/or for preparing an amphiphilic branched polysiloxaneprepolymer of the invention. It is understood that the secondethylenically-functionalizing vinylic monomer can be different from butpreferably identical to the first ethylenically functionalizing vinylicmonomer (used in preparing the partially ethylenically functionalizedpolysiloxane). Examples of ethylenically-functionalizing vinylicmonomers include without limitation C₂ to C₆ hydroxylalkyl(meth)acrylate, C₂ to C₆ hydroxyalkyl (meth)acrylamide, allylalcohol,allylamine, amino-C₂-C₆ alkyl (meth)acrylate, C₁-C₆ alkylamino-C₂-C₆alkyl (meth)acrylate, vinylamine, amino-C₂-C₆ alkyl (meth)acrylamide,C₁-C₆ alkylamino-C₂-C₆ alkyl (meth)acrylamide, acrylic acid, C₁-C₄alkylacrylic acid (e.g., methacrylic ethylacrylic acid, propylacrylicacid, butylacrylic acid), N-[tris(hydroxymethyl)-methyl]acrylamide,N,N-2-acrylamidoglycolic acid, beta methyl-acrylic acid (crotonic acid),alpha-phenyl acrylic acid, beta-acryloxy propionic acid, sorbic acid,angelic acid, cinnamic acid, 1-carboxy-4-phenyl butadiene-1,3, itaconicacid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid,maleic acid, fumaric acid, aziridinyl C₁-C₁₂ alkyl (meth)acrylate (e.g.,2-(1-aziridinyl) ethyl (meth)acrylate, 3-(1-aziridinyl) propyl(meth)acrylate, 4-(1-aziridinyl) butyl (meth)acrylate, 6-(1-aziridinyl)hexyl (meth)acrylate, or 8-(1-aziridinyl) octyl (meth)acrylate),glycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether,(meth)acrylic acid halide groups (—COX, X=Cl, Br, or I), C₁ to C₆isocyanatoalkyl (meth)acrylate, azlactone-containing vinylic monomers(e.g., 2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-ethyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-butyl-1,3-oxazolin-5-one,2-vinyl-4,4-dibutyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-dodecyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-diphenyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-pentamethylene-1,3-oxazolin-5-one,2-isopropenyl-4,4-tetramethylene-1,3-oxazolin-5-one,2-vinyl-4,4-diethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-nonyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-phenyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-benzyl-1,3-oxazolin-5-one,2-vinyl-4,4-pentamethylene-1,3-oxazolin-5-one, and2-vinyl-4,4-dimethyl-1,3-oxazolin-6-one, with2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one (VDMO) and2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one (IPDMO) as preferredazlactone-containing vinylic monomers), and combinations thereof.

Preferably, the first reactive functional group of the firstethylenically functionalizing vinylic monomer, the fourth reactivefunctional group of the second ethylenically functionalizing vinylicmonomer, the second reactive functional groups of the functionalpolysiloxane compound, and the third reactive functional group of thechain transfer agent, independently of each other, are selected from thegroup consisting of amino group (—NHR′ as defined above), hydroxylgroup, carboxylic acid group, acid halide groups (—COX, X=Cl, Br, or I),acid anhydrate group, aldehyde group, azlactone group, isocyanate group,epoxy group, aziridine group, amide groups (—CONH₂), and combinationsthereof, more preferably selected from the group consisting of aminogroup (—NHR′ as defined above), hydroxyl group, carboxylic acid group,acid halide groups (—COX, X=Cl, Br, or I), azlactone group, isocyanategroup, epoxy group, aziridine group, and combinations thereof, providedthat one first or fourth reactive functional group can react with onesecond or third reactive functional group in the presence or absence ofa coupling agent to form a covalent linkage.

It is understood that a partially ethylenically functionalizedpolysiloxane comprises at least one polysiloxane vinylic monomer ormacromer having at least one ethylenically unsaturated groups and atleast one reactive functional group. Such polysiloxane vinylic monomeror macromer having at least one reactive functional group gives rise toformation of dangling polysiloxane chains each terminated with onereactive functional group in an amphiphilic branched polysiloxanecopolymer and eventually to the formation of dangling polysiloxanechains each terminated with one ethylenically unsaturated group in anamphiphilic branched polysiloxane prepolymer of the invention. Where apolysiloxane vinylic monomer or macromer has two or more ethylenicallyunsaturated groups and at least one reactive functional group, it canserve also a polysiloxane crosslinker.

Preferably, a functional polysiloxane used for preparing a partiallyethylenically functionalized polysiloxane is represented by formula (1).More preferably, an ethylenically functionalizing vinylic monomer isreacted with a functional polysiloxane compound of formula (1) at amolar equivalent of from 70% to about 90% to obtain a partiallyethylenically functionalized polysiloxane.

In accordance with this aspect of the invention, any suitablehydrophilic vinylic monomers can be used in the preparation of anamphiphilic branched polysiloxane prepolymer of the invention. Suitablehydrophilic vinylic monomers are, without this being an exhaustive list,hydroxyl-substituted C₁-C₆ alkyl (meth)acrylates, hydroxyl-substitutedC₁-C₆ alkyl (meth)acrylamides, hydroxyl-substituted C₁-C₆ alkyl vinylethers, C₁ to C₆ alkyl (meth)acrylamide, di-(C₁-C₆ alkyl)(meth)acrylamide, N-vinylpyrrole, N-vinyl-2-pyrrolidone,2-vinyloxazoline, 2-vinyl-4,4′-dialkyloxazolin-5-one, 2- and4-vinylpyridine, olefinically unsaturated carboxylic acids having atotal of 3 to 6 carbon atoms, amino-substituted C₁-C₆ alkyl- (where theterm “amino” also includes quaternary ammonium), mono(C₁-C₆ alkylamino)(C₁-C₆ alkyl) and di(C₁-C₆ alkyl amino)(C₁-C₆ alkyl)(meth)acrylates or (meth)acrylamides, allyl alcohol, vinylamine, N-vinylC₁-C₆ alkylamide, N-vinyl-N-C₁-C₆ alkyl amide, and combinations thereof.

Examples of preferred hydrophilic vinylic monomers areN,N-dimethylacrylamide (DMA), N,N-dimethylmethacrylamide (DMMA),2-acrylamidoglycolic acid, 3-acryloylamino-1-propanol, N-hydroxyethylacrylamide, N-[tris(hydroxymethyl)methyl]-acrylamide,N-methyl-3-methylene-2-pyrrolidone, 1-ethyl-3-methylene-2-pyrrolidone,1-methyl-5-methylene-2-pyrrolidone, 1-ethyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-n-propyl-3-methylene-2-pyrrolidone,1-n-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone,1-n-butyl-3-methylene-2-pyrrolidone,1-tert-butyl-3-methylene-2-pyrrolidone, 2-hydroxyethylmethacrylate(HEMA), 2-hydroxyethyl acrylate (HEA), hydroxypropyl acrylate,hydroxypropyl methacrylate (HPMA), trimethylammonium 2-hydroxypropylmethacrylate hydrochloride, aminopropyl methacrylatehydrochloride, dimethylaminoethyl methacrylate (DMAEMA), glycerolmethacrylate (GMA), N-vinyl-2-pyrrolidone (NVP), allyl alcohol,vinylpyridine, a C₁-C₄-alkoxy polyethylene glycol (meth)acrylate havinga weight average molecular weight of up to 1500, methacrylic acid,N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide,N-vinyl-N-methyl acetamide, N-vinyl caprolactam, and mixtures thereof.Among those preferred hydrophilic vinylic monomers, those free of anyreactive functional group are particularly preferred for incorporatingin the polymerizable composition for preparing the amphiphilic branchedpolysiloxane copolymer.

In accordance with this aspect of the invention, any suitablehydrophobic vinylic monomers can be used in the preparation of anamphiphilic branched polysiloxane prepolymer of the invention. Examplesof preferred hydrophobic vinylic monomers include methyl (meth)acrylate,ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate,butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate,t-butyl (meth)acrylate, cyclohexylacrylate, 2-ethylhexylacrylate, vinylacetate, vinyl propionate, vinyl butyrate, vinyl valerate, styrene,chloroprene, vinyl chloride, vinylidene chloride, acrylonitrile,1-butene, butadiene, methacrylonitrile, vinyl toluene, vinyl ethylether, perfluorohexylethyl-thio-carbonyl-aminoethyl-methacrylate,isobornyl methacrylate, trifluoroethyl methacrylate,hexafluoro-isopropyl methacrylate, hexafluorobutyl methacrylate, asilicone-containing vinylic monomer, and mixtures thereof. Mostpreferably, the polymerizable composition comprises a bulky hydrophobicvinylic monomer. Preferred bulky hydrophobic vinylic monomers includewithout limitationN-[tris(trimethylsiloxy)silylpropyl]-(meth)acrylamide;N-[tris(dimethylpropylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylphenylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]acrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;3-methacryloxy propylpentamethyldisiloxane;tris(trimethylsilyloxy)silylpropyl methacrylate (TRIS);(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane);(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane;3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)methylsilane;N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silylcarbamate; 3-(trimethylsilyl)propylvinyl carbonate;3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane;3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl vinylcarbonate; trimethylsilylmethyl vinyl carbonate; t-butyl (meth)acrylate,cyclohexylacrylate, isobornyl methacrylate, a polysiloxane-containingvinylic monomer (having 3 to 8 silicone atoms), and combinationsthereof.

It is believed that the presence of such bulky hydrophobic vinylicmonomer in the polysiloxane prepolymer may be able to minimize oreliminate optical defects (permanent deformations) derived from handlingduring manufacturing in lenses made from a lens-forming compositioncomprising the polysiloxane prepolymer. Such deformation or opticaldefect refers to permanent folding marks observed on the lens by aContact Lens Optical Quality Analyzer (CLOQA) after the lens is foldedmanually as described in Example 1 of copending U.S. patent applicationSer. No. 12/456,364 (herein incorporated by reference in its entirety).It is believed that when a bulky hydrophobic vinylic monomer is present,resultant lenses exhibit a ‘healing’ effect that eliminated the opticaldefects (i.e., the folding marks become transient and can disappearafter a short time period, e.g., about 15 minutes or less).

In accordance with the invention, a chain transfer agent may compriseone or more thiol groups, for example two or most preferably one thiolgroup. Where a chain transfer agent comprises a reactive functionalgroup (e.g., hydroxyl, amino, or carboxylic acid group) in addition tothiol group, such chain transfer agent can be used to providefunctionality for subsequent addition of an ethylenically unsaturatedgroup. Suitable chain transfer agents include organic primary thiols ormercaptans having a further reactive functional group such as, forexample, hydroxy, amino, N—C₁-C₆-alkylamino, carboxy or a suitablederivative thereof. A preferred chain transfer agent is a cycloaliphaticor preferably aliphatic thiol having from 2 to about 24 carbon atoms andhaving a further reactive functional group selected from amino, hydroxyand carboxy; accordingly, the preferred chain transfer agents arealiphatic mercapto carboxylic acids, hydroxymercaptans oraminomercaptans. Examples of preferred chain transfer agents are2-mercaptoethanol, 2-aminoethane thiol (cysteamine), 2-mercaptopropinicacid, thioglycolic acid, thiolactic acid, ethanedithiol, propanedithiol,and combinations thereof. In case of an amine or a carboxylic acid, thechain transfer agent may be in form of the free amine or acid or,preferably, in form of a suitable salt thereof, for example ahydrochloride in case of an amine or a sodium, potassium or amine saltin case of an acid.

In a preferred embodiment, the polymerizable composition comprises afirst hydrophilic vinylic monomer free of any reactive functional groupcapable of participating in a coupling reaction with the secondethylenically functionalizing vinylic monomer and a second hydrophilicvinylic monomer having a reactive functional group capable ofparticipating the coupling reaction with the second ethylenicallyfunctionalizing vinylic monomer, wherein the first and secondhydrophilic vinylic monomers are present in the polymerizablecomposition at a ratio of from about 5:1 to about 30:1. The firsthydrophilic vinylic monomer is preferably selected from the groupconsisting of N,N-dimethyl (meth)acrylamide,N-methyl-3-methylene-2-pyrrolidone, 1-ethyl-3-methylene-2-pyrrolidone,1-methyl-5-methylene-2-pyrrolidone, 1-ethyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-n-propyl-3-methylene-2-pyrrolidone,1-n-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone,1-n-butyl-3-methylene-2-pyrrolidone,1-tert-butyl-3-methylene-2-pyrrolidone, dimethylaminoethyl(meth)acrylate, N-vinyl-2-pyrrolidone, a C₁-C₄-alkoxy polyethyleneglycol (meth)acrylate, N-vinyl formamide, N-vinyl acetamide, N-vinylisopropylamide, N-vinyl-N-methyl acetamide, and mixtures thereof; andthe second hydrophilic vinylic monomer is preferably selected from thegroup consisting of hydroxyl-substituted C₁-C₄ alkyl (meth)acrylate,hydroxyl-substituted C₁-C₄ alkyl (meth)acrylamide, amino-substitutedC₁-C₄ alkyl (meth)acrylate, amino-substituted C₁-C₄ alkyl(meth)acrylamide, allyl alcohol, allyl amine, and mixture thereof.

In another preferred embodiment, an amphiphilic branched polysiloxanecopolymer for making an amphiphilic branched polysiloxane prepolymer ofthe invention is obtained by polymerizing a polymerizable compositioncomprising: (a) from about 10% to about 94%, preferably from about 20%to about 80%, more preferably from about 40% to about 65%, by weight ofa partially (40% to about 95%, preferably from about 50% to about 95%,more preferably from about 60% to about 92%, even more preferably fromabout 70% to about 90%) ethylenically-functionalized polysiloxane (i.e.,a partially-ethylenically-functionalized polysiloxane); (b) from about5% to about 75%, preferably from about 10% to about 65%, more preferablyfrom about 15% to about 55%, even more preferably from about 20% toabout 45%, by weight of at least one hydrophilic vinylic monomer; (c)from 0 to about 55%, preferably from about 5% to about 45%, morepreferably from about 10% to about 40%, even more preferably from about15% to about 30%, by weight of a bulky hydrophobic vinylic monomer; (d)from about 0.25% to about 5%, preferably from about 0.5% to about 4%,more preferably from about 0.75% to about 3%, even more preferably fromabout 1% to about 2%, by weight of a chain transfer agent other than aRAFT agent, wherein the chain transfer agent optionally but preferablyincluding a reactive functional group; (e) from 0 to 5% by weight,preferably from about 0.2% to 4% by weight, more preferably from about0.3% to about 2.5% by weight, even more preferably from about 0.5% toabout 1.8%, by weight of a polymerizable UV-absorbing compound; and (f)from about 0.1% to about 5%, preferably from about 0.2% to about 4%,more preferably from about 0.3% to about 3%, even more preferably fromabout 0.4% to about 1.5%, by weight of a free-radical initiator (aphotoinitiator or a thermal initiator, preferably a thermal initiator).Percentages by weight of the above-listed components are relative to thecombined weight of all polymerizable components (which can includeadditional polymerizable components not listed here).

Preferred polymerizable UV absorbers include without limitation2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole,2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole,2-(2-hydroxy-3-methacrylamido methyl-5-tert octylphenyl)benzotriazole,2-(2′-hydroxy-5′-methacrylamidophenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-5′-methacrylamidophenyl)-5-methoxybenzotriazole,2-(2′-hydroxy-5′-methacryloxypropyl-3′-t-butyl-phenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-5′-methacryloxyethylphenyl)benzotriazole,2-(2′-hydroxy-5′-methacryloxypropylphenyl)benzotriazole,2-hydroxy-4-acryloxy alkoxy benzophenone, 2-hydroxy-4-methacryloxyalkoxy benzophenone, allyl-2-hydroxybenzophenone,2-hydroxy-4-methacryloxy benzophenone. A polymerizable UV-absorbingagent is generally is present in the polymerizable composition forpreparing a polysiloxane copolymer which is ethylenically functionalizedin turn to obtain a polysiloxane prepolymer of the invention in anamount sufficient to render a contact lens, which is made from a lensforming material including the prepolymer and which absorbs at leastabout 80 percent of the UV light in the range of from about 280 nm toabout 370 nm that impinges on the lens. A person skilled in the art willunderstand that the specific amount of UV-absorbing agent used in thepolymerizable composition will depend on the molecular weight of theUV-absorbing agent and its extinction coefficient in the range fromabout 280 to about 370 nm. In accordance with the invention, thepolymerizable composition comprises about 0.2% to about 5.0%, preferablyabout 0.3% to about 2.5%, more preferably about 0.5% to about 1.8%, byweight of a UV-absorbing agent.

The polymerizable composition for preparing an amphiphilic branchedpolysiloxane copolymer can further comprise a polysiloxane-containingvinylic macromer. A polysiloxane-containing vinylic macromer can beprepared according to any known procedures, for example, those describedin U.S. Pat. Nos. 4,136,250, 4,486,577, 4,605,712, 5,034,461, 5,416,132,and 5,760,100, herein incorporated by reference in their entireties.

Examples of preferred polysiloxane-containing vinylic monomers ormacromers include without limitation mono-(meth)acrylate-terminatedpolydimethylsiloxanes of various molecular weight (e.g.,mono-3-methacryloxypropyl terminated, mono-butyl terminatedpolydimethylsiloxane or mono-(3-methacryloxy-2-hydroxypropyloxy)propylterminated, mono-butyl terminated polydimethylsiloxane);mono-vinyl-terminated, mono-vinyl carbonate-terminated or mono-vinylcarbamate-terminated polydimethylsiloxanes of various molecular weight;polysiloxanylalkyl (meth)acrylic monomers; hydroxyl-functionalizedsiloxane-containing vinylic monomers or macromers; and mixtures thereof.Examples of preferred polysiloxane-containing crosslinkers includewithout limitation di-(meth)acrylated polydimethylsiloxanes (or socalled polysiloxane crosslinkers) of various molecular weight; di-vinylcarbonate-terminated polydimethylsiloxanes (polysiloxane crosslinkers);di-vinyl carbamate-terminated polydimethylsiloxane (polysiloxanecrosslinkers); di-vinyl terminated polydimethylsiloxanes (polysiloxanecrosslinkers); di-(meth)acrylamide-terminated polydimethylsiloxanes(polysiloxane crosslinkers); bis-3-methacryloxy-2-hydroxypropyloxypropylpolydimethylsiloxane (polysiloxane crosslinker);N,N,N′,N′-tetrakis(3-methacryloxy-2-hydroxypropyl)-alpha,omega-bis-3-aminopropyl-polydimethylsiloxane(polysiloxane crosslinkers); siloxane-containing macromer selected fromthe group consisting of Macromer A, Macromer B, Macromer C, and MacromerD described in U.S. Pat. No. 5,760,100 (herein incorporated by referencein its entirety); the reaction products of glycidyl methacrylate withamino-functional polydimethylsiloxanes; polysiloxane-containingcrosslinkers disclosed in U.S. Pat. Nos. 4,136,250, 4,153,641,4,182,822, 4,189,546, 4,343,927, 4,254,248, 4,355,147, 4,276,402,4,327,203, 4,341,889, 4,486,577, 4,543,398, 4,605,712, 4,661,575,4,684,538, 4,703,097, 4,833,218, 4,837,289, 4,954,586, 4,954,587,5,010,141, 5,034,461, 5,070,170, 5,079,319, 5,039,761, 5,346,946,5,358,995, 5,387,632, 5,416,132, 5,451,617, 5,486,579, 5,962,548,5,981,675, 6,039,913, and 6,762,264 (here incorporated by reference intheir entireties); polysiloxane-containing crosslinkers disclosed inU.S. Pat. Nos. 4,259,467, 4,260,725, and 4,261,875 (herein incorporatedby reference in their entireties); di- and tri-block crosslinkersconsisting of polydimethylsiloxane and polyalkyleneoxides (e.g.,methacrylate end cappedpolyethyleneoxide-block-polydimethylsiloxane-block-polyethyleneoxide);and mixtures thereof.

A further class of preferred polysiloxane-containing crosslinkers issilicon-containing prepolymers comprising hydrophilic segments andhydrohphobic segments. Any suitable of silicone-containing prepolymerswith hydrophilic segments and hydrohphobic segments can be used in theinvention. Examples of such silicone-containing prepolymers includethose described in commonly-owned U.S. Pat. Nos. 6,039,913, 6,043,328,7,091,283, 7,268,189 and 7,238,750, 7,521,519; commonly-owned US patentapplication publication Nos. US 2008-0015315 A1, US 2008-0143958 A1, US2008-0143003 A1, US 2008-0234457 A1, US 2008-0231798 A1, andcommonly-owned U.S. patent application Ser. Nos. 12/313,546, 12/616,166and 12/616,169; all of which are incorporated herein by references intheir entireties.

Polymerization of a polymerizable composition for preparing anamphiphilic branched polysiloxane copolymer is based on well-knownradical chain growth polymerization and can be performed according toany known methods and in any containers (reactors) suitable forpolymerization. The polymerization is preferably initiated thermally. Apolymerizable composition for preparing an amphiphilic branchedpolysiloxane can be prepared by dissolving all of components in anysuitable solvent known to a person skilled in the art.

The obtained amphiphilic branched polysiloxane copolymer then isethylenically functionalized by reacting it with a secondethyenically-functionalizing vinylic monomer having a fourth reactivefunctional group to obtain an amphiphilic branched polysiloxaneprepolymer of the invention, provided that the fourth reactive group canreact with one of the terminal second reactive functional groups and thethird functional groups (if available) of the amphiphilic branchedpolysiloxane copolymer, in the presence or absence of a coupling agent,to form a covalent linkage. It is understood that, during this step ofethylenical functionalization, the unreacted functional polysiloxane,which is inherently presented in the partially ethylenicallyfunctionalized polysiloxane, is also ethylenically functionalized toform a polysiloxane crosslinker that can be used together with theresultant amphiphilic branched polysiloxane prepolymer in preparing alens formulation for making silicone hydrogel contact lenses.

In accordance with the invention, the molar equivalent ratio of thesecond ethylenically functionalizing vinylic monomer to the amphiphilicpolysiloxane copolymer is greater than 1, preferably from about 1 toabout 1.2, more preferably from about 1 to about 1.1, even morepreferably from about 1 to 1.05. It is understand that the calculationof the molar equivalent ratio should account all of possible reactivefunctional groups of the amphiphilic branched copolymer, including thosederived from the partially ethylenically functionalized polysiloxane,from the chain transfer agent, from any other polymerizable componentshaving a reactive functional group in the polymerizable composition.Such calculation can be done based on starting materials for preparingthe amphiphilic branched polisiloxane copolymer. The excess amount ofthe second ethylenically functionalizing vinylic monomer can be (butpreferably not be) removed from the resultant amphiphilic branchedpolysiloxane prepolymer before the prepolymer is used in preparing alens formulation for making silicone hydrogel contact lenses.

In accordance with the invention, the weight percentages of thecomponents of an amphiphilic branched polysiloxane prepolymer isdetermined by the polymerizable composition or mixture based on thetotal weight of all the polymerizable components of the composition ormixture used for preparing an amphiphilic branched polysiloxanecopolymer which in turn is ethylenically functionalized to form theprepolymer of the invention. For example, if a polymerizable mixture,for preparing an amphiphilic branched polysiloxane copolymer which is inturn ethylenically functionalized to form the prepolymer of theinvention, comprises about 44% by weight of a 80%-ethylenicallyfunctionalized linear polydimethylsiloxane (which contains 64% of alinear polysiloxane crosslinker with two ethylenically unsaturatedgroups, 32% of a linear polysiloxane with one ethylenically-unsaturatedgroup and one reactive functional group for ethylenicalfunctionalization, 4% of a linear polysiloxane with two terminalreactive functional groups which is not incorporated into theamphiphilic branched prepolymer, the percentaged are calculated asdescribed above), about 28.5% by weight of at least one hydrophilicvinylic monomer, about 26% by weight of a bulky hydrophobic vinylicmonomer (e.g., TRIS or the like), and about 1.5% of a chain transferagent (e.g., mercaptoethanol), then the resultant amphiphilic branchedprepolymer comprise about 28% by weight of polysiloxane crosslinkingunits (44%×64%×100), about 14% by weight of dangling polysiloxane chainseach of which is terminated with an ethylenically unsaturated group(44%×32%×100), about 28.5% by weight of hydrophilic monomeric units,about 26% by weight of the bulky hydrophobic monomeric units, and about1.5% by weight of chain transfer units. A person skilled in the art willknow well how to determine the percentages of each components of anamphiphilic branched prepolymer according to the procedure describedabove for the illustrative example.

An amphiphilic branched polysiloxane prepolymer of the invention canfind particular uses as a lens forming material for preparing siliconehydrogel contact lenses. It will be particularly advantageous to use asan amphiphilic branched polysiloxane prepolymer of the inventiontogether with a small amount (i.e., less than 20% by weight relative tothe total amount of all polymerizable components) of one or more vinylicmonomers in preparing a lens-forming composition for making siliconehydrogel contact lenses. Curing of such lens forming composition inmolds would amount to a two-stage curing process, the first one being aoff-line curing (or precuring) of a lens formulation in a container andthe other being in-line curing of a lens formulation in molds. Suchlens-forming composition can offer the following advantages. First, theconcentration of one or more vinylic monomers in the lens-formingcomposition can be reduced and as such, shrinkage occurring uponpolymerization of the lens forming composition in molds for makingcontact lenses can be substantially reduced. Second, ethylenicallygroups of an amphphilic branched polysiloxane prepolymer are readilyaccessible for radical chain growth polymerization, because they arelocated at the terminals of polymer chains. The curing time of the lensforming composition in molds can be relatively short comparing to a lensforming composition made of a monomer mixture (i.e., greater than 20% byweight of one or more vinylic monomer relative to the total amount ofall polymerizable components). Third, the viscosity of the lens formingcomposition can be relatively low comparing to a lens formingcomposition made of one or more prepolymers, because of the presence ofone or more vinylic monomers.

It should be understood that although various preferred embodiments ofthe invention may be separately described above, they can be combined inany desirable fashion to arrive at different preferred embodiments ofthe invention.

In a second aspect, the invention provides a method for making siliconehydrogel contact lenses. The method comprises the steps of: (i)obtaining an amphiphilic branched polysiloxane prepolymer, wherein theamphiphilic branched polysiloxane prepolymer comprises (a) from about 5%to about 75%, preferably from about 10% to about 65%, more preferablyfrom about 15% to about 55%, even more preferably from about 20% toabout 45%, by weight of hydrophilic monomeric units derived from atleast one hydrophilic vinylic monomer, (b) from about 1% to about 85%,preferably from about 2.5% to about 75%, more preferably from about 5%to about 65%, by weight of polysiloxane crosslinking units derived fromat least one polysiloxane crosslinker having two or more terminalethylenically-unsaturated groups, (c) from about 2% to about 48%,preferably from about 3% to about 38%, more preferably from from about4% to about 28%, by weight of dangling polysiloxane chains each of whichis terminated with an ethylenically unsaturated group, and (d) fromabout 0.25% to about 5%, preferably from about 0.5% to about 4%, morepreferably from about 0.75% to about 3%, even more preferably from about1% to about 2%, by weight of chain-transfer units derived from a chaintransfer agent other than a RAFT agent; (ii) using the amphiphilicbranched polysiloxane prepolymer to prepare a lens-forming compositionwhich comprises (a) from about 60% to about 99%, preferably from about75% to about 97%, more preferably from about 85% to about 95%, by weightof the amphiphilic branched polysiloxane prepolymer, (b) from about 0.1%to about 5%, preferably from about 0.3% to about 3%, more preferablyfrom about 0.4% to about 1.5%, by weight of a free-radical initiator (aphotoinitiator or a thermal initiator, preferably a photoinitiator), and(c) from 0 to about 20%, preferably from about 2% to about 16%, morepreferably from about 4% to about 12%, by weight of at least onepolymerizable component selected from the group consisting of ahydrophilic vinylic monomer, a silicone-containing vinylic monomer ormacromer, a hydrophobic vinylic monomer, a linear polysiloxanecrosslinker terminated with two ethylenically-unsaturated groups, acrosslinking agent having a molecular weight of less than 700 Daltons, apolymerizable UV-absorbing agent, and mixtures thereof, wherein thepercentages by weight of components (a)-(c) are relative to the totalamount of all polymerizable components (including those not listedabove) in the lens-forming composition; (iii) introducing thelens-forming composition into a mold, wherein the mold has a first moldhalf with a first molding surface defining the anterior surface of acontact lens and a second mold half with a second molding surfacedefining the posterior surface of the contact lens, wherein said firstand second mold halves are configured to receive each other such that acavity for receiving the lens-forming material is formed between saidfirst and second molding surfaces; and (iv) polymerizing thelens-forming material in the cavity to form a silicone hydrogel contactlens.

Various embodiments including preferred embodiments of amphiphilicbranched polysiloxane prepolymers, free-radical initiators, chaintransfer agents, hydrophilic vinylic monomers, silicone-containingvinylic monomers or macromers, hydrophobic vinylic monomers,crosslinking agents having a molecular weight of less than 700 Daltons,polymerizable UV-absorbing agents, and linear polysiloxane crosslinkersterminated with two ethylenically-unsaturated groups are described aboveand can be used in this aspect of the invention.

Preferably, an amphiphilic branched polysiloxane prepolymer is obtainedaccording to a process comprising the steps of: (i) obtaining apartially ethylenically-functionalized polysiloxane, wherein thepartially ethylenically-functionalized polysiloxane is a mixture ofreaction products obtained by reacting a first functionalizing vinylicmonomer having a first reactive functional group with a functionalpolysiloxane compound having two or more second reactive functionalgroups at a molar equivalent ratio of from about 40% to about 95%,preferably from about 50% to about 95%, more preferably from about 60%to about 92%, even more preferably from about 70% to about 90% (theethylenically-functionalizing vinylic monomer to the functionalpolysiloxane compound), wherein each first reactive functional groupreacts with one second reactive functional group in the presence orabsence of a coupling agent to form a covalent bond or linkage, whereinthe mixture of reaction product comprises at least one polysiloxanecrosslinkers having at least two ethylenically unsaturated groups and atleast one polysiloxane vinylic monomer or macromer having at least onesecond reactive functional group and at least one ethylenicallyunsaturated group; (ii) using the amphiphilic branched polysiloxanecopolymer to prepare a polymerizable composition, wherein thepolymerizable composition comprises at least one hydrophilic vinylicmonomer, a chain transfer agent which is not a RAFT agent and optionally(but preferably) includes a third reactive functional group, and afree-radical initiator; (iii) polymerizing the polymerizable compositionto form an amphiphilic branched polysiloxane copolymer comprisinghydrophilic monomeric units derived from said at least one hydrophilicvinylic monomer, polysiloxane crosslinking units derived from thepolysiloxane crosslinker, dangling polysiloxane chains each terminatedwith a second reactive functional group and derived from thepolysiloxane vinylic monomer or macromer, and chain transfer units withor without third reactive functional groups derived from the chaintransfer agent; (iv) reacting the branched polysiloxane copolymer with asecond ethylenically functionalizing vinylic monomer having a fourthreactive functional group which reacts with one second or third reactivefunctional group of the branched polysiloxane copolymer in the presenceor absence of a coupling agent to form a covalent linkage, therebyforming the amphiphilic branched polysiloxane prepolymer having danglingpolysiloxane chains each of which is terminated with oneethylenically-unsaturated group.

Various embodiments including various preferred embodiments offunctional polysiloxanes with reactive functional groups,ethylenically-functionalizing vinylic monomers, hydrophilic vinylicmonomers, hydrophobic vinylic monomers, bulky hydrophobic vinylicmonomers, free-radical initiators, polymerizable UV-absorbing agents,chains transfer agents, and solvents, and polymerizable compositions forpreparing an amphiphilic branched polysiloxane copolymer are describedabove (e.g., for the first aspect of the invention) and can be used inthis aspect of the invention.

In accordance with the invention, the first and secondethylenically-functionalizing vinylic monomers can be different from,but preferably identical to each other. Preferably, the molar equivalentratio of the second ethylenically functionalizing vinylic monomer to theamphiphilic polysiloxane copolymer is greater than 1, preferably fromabout 1 to about 1.2, more preferably from about 1 to about 1.1, evenmore preferably from about 1 to 1.05. The amphiphilic branchedpolysiloxane copolymer can be (but preferably is not) purified prior toethylenical functionalization. The excess amount of the secondethylenically functionalizing vinylic monomer can be (but preferably notbe) removed from the resultant amphiphilic branched polysiloxaneprepolymer before the prepolymer is used in preparing a lens formulationfor making silicone hydrogel contact lenses.

The obtained amphiphilic branched polysiloxane prepolymer can bedirectly used in preparation of a lens-forming composition for makingsilicone hydrogel contact lenses. However, if the solvent used inpreparing amphiphilic branched polysiloxane prepolymer is not a solventdesired for preparing a lens-forming composition, it is desired toexchange the solvent according to any suitable techniques known to aperson skilled in the art (for example, repeated cycles of condensationand dilution with a desired solvent). Alternatively, the obtainedamphiphilic branched polysiloxane prepolymer can be purified by anyknown suitable techniques known to a person skilled in the art.

It must be understood that a lens-forming composition can also comprisevarious components, such as, for example, a hydrophilic vinylic monomer,a hydrophobic vinylic monomer, a bulky hydrophobic vinylic monomer, avisibility tinting agent (e.g., dyes, pigments, or mixtures thereof), apolymerizable UV-absorbing agent, antimicrobial agents (e.g., preferablysilver nanoparticles), a bioactive agent, leachable lubricants,leachable tear-stabilizing agents, and mixtures thereof, as known to aperson skilled in the art.

The bioactive agent incorporated in the polymeric matrix is any compoundthat can prevent a malady in the eye or reduce the symptoms of an eyemalady. The bioactive agent can be a drug, an amino acid (e.g., taurine,glycine, etc.), a polypeptide, a protein, a nucleic acid, or anycombination thereof. Examples of drugs useful herein include, but arenot limited to, rebamipide, ketotifen, olaptidine, cromoglycolate,cyclosporine, nedocromil, levocabastine, lodoxamide, ketotifen, or thepharmaceutically acceptable salt or ester thereof. Other examples ofbioactive agents include 2-pyrrolidone-5-carboxylic acid (PCA), alphahydroxyl acids (e.g., glycolic, lactic, malic, tartaric, mandelic andcitric acids and salts thereof, etc.), linoleic and gamma linoleicacids, and vitamins (e.g., B5, A, B6, etc.).

Examples of leachable lubricants include without limitation mucin-likematerials (e.g., polyglycolic acid) and non-crosslinkable hydrophilicpolymers (i.e., without ethylenically unsaturated groups).

Any hydrophilic polymers or copolymers without any ethylenicallyunsaturated groups can be used as leachable lubricants. Preferredexamples of non-crosslinkable hydrophilic polymers include, but are notlimited to, polyvinyl alcohols (PVAs), polyamides, polyimides,polylactone, a homopolymer of a vinyl lactam, a copolymer of at leastone vinyl lactam in the presence or in the absence of one or morehydrophilic vinylic comonomers, a homopolymer of acrylamide ormethacrylamide, a copolymer of acrylamide or methacrylamide with one ormore hydrophilic vinylic monomers, polyethylene oxide (i.e.,polyethylene glycol (PEG)), a polyoxyethylene derivative,poly-N-N-dimethylacrylamide, polyacrylic acid, poly 2 ethyl oxazoline,heparin polysaccharides, polysaccharides, and mixtures thereof. Theweight-average molecular weight M_(n) of the non-crosslinkablehydrophilic polymer is preferably from 5,000 to 500,000, more preferablyfrom 10,000 to 300,000, even more preferably from 20,000 to 100,000.

Examples of leachable tear-stabilizing agents include, withoutlimitation, phospholipids, monoglycerides, diglycerides, triglycerides,glycolipids, glyceroglycolipids, sphingolipids, sphingo-glycolipids,fatty alcohols, fatty acids, mineral oils, and mixtures thereof.Preferably, a tear stabilizing agent is a phospholipid, a monoglyceride,a diglyceride, a triglyceride, a glycolipid, a glyceroglycolipid, asphingolipid, a sphingo-glycolipid, a fatty acid having 8 to 36 carbonatoms, a fatty alcohol having 8 to 36 carbon atoms, or a mixturethereof.

A lens-forming composition can be prepared by dissolving all of thedesirable components in any suitable solvent known to a person skilledin the art. Examples of suitable solvents are described above and can beused in this aspect of the invention.

Lens molds for making contact lenses are well known to a person skilledin the art and, for example, are employed in cast molding or spincasting. For example, a mold (for cast molding) generally comprises atleast two mold sections (or portions) or mold halves, i.e. first andsecond mold halves. The first mold half defines a first molding (oroptical) surface and the second mold half defines a second molding (oroptical) surface. The first and second mold halves are configured toreceive each other such that a lens forming cavity is formed between thefirst molding surface and the second molding surface. The moldingsurface of a mold half is the cavity-forming surface of the mold and indirect contact with lens-forming material.

Methods of manufacturing mold sections for cast-molding a contact lensare generally well known to those of ordinary skill in the art. Theprocess of the present invention is not limited to any particular methodof forming a mold. In fact, any method of forming a mold can be used inthe present invention. The first and second mold halves can be formedthrough various techniques, such as injection molding or lathing.Examples of suitable processes for forming the mold halves are disclosedin U.S. Pat. No. 4,444,711 to Schad; U.S. Pat. No. 4,460,534 to Boehm etal.; U.S. Pat. No. 5,843,346 to Morrill; and U.S. Pat. No. 5,894,002 toBoneberger et al., which are also incorporated herein by reference.

Virtually all materials known in the art for making molds can be used tomake molds for making contact lenses. For example, polymeric materials,such as polyethylene, polypropylene, polystyrene, PMMA, Topas® COC grade8007-S10 (clear amorphous copolymer of ethylene and norbornene, fromTicona GmbH of Frankfurt, Germany and Summit, N.J.), or the like can beused. Other materials that allow UV light transmission could be used,such as quartz glass and sapphire.

In a preferred embodiment, reusable molds are used and the lens-formingcomposition is cured (i.e., polymerized) actinically under a spatiallimitation of actinic radiation to form a silicone hydrogel contactlens. Examples of preferred reusable molds are those disclosed in U.S.patent application Ser. No. 08/274,942 filed Jul. 14, 1994, Ser. No.10/732,566 filed Dec. 10, 2003, Ser. No. 10/721,913 filed Nov. 25, 2003,and U.S. Pat. No. 6,627,124, which are incorporated by reference intheir entireties. Reusable molds can be made of quartz, glass, sapphire,CaF₂, a cyclic olefin copolymer (such as for example, Topas® COC grade8007-S10 (clear amorphous copolymer of ethylene and norbornene) fromTicona GmbH of Frankfurt, Germany and Summit, N.J., Zeonex® and Zeonor®from Zeon Chemicals LP, Louisville, Ky.), polymethylmethacrylate (PMMA),polyoxymethylene from DuPont (Delrin), Ultem® (polyetherimide) from G.E.Plastics, PrimoSpire®, etc.

In accordance with the invention, the lens-forming composition can beintroduced (dispensed) into a cavity formed by a mold according to anyknown methods.

After the lens-forming composition is dispensed into the mold, it ispolymerized to produce a contact lens. Crosslinking may be initiatedthermally or actinically, preferably by exposing the lens-formingcomposition in the mold to a spatial limitation of actinic radiation tocrosslink the polymerizable components in the lens-forming composition.The crosslinking according to the invention may be effected in a veryshort time, e.g. in ≦about 120 seconds, preferably in ≦about 80 seconds,more preferably in 50 about seconds, even more preferably in ≦about 30seconds, and most preferably in 5 to 30 seconds.

Where the lens-forming composition comprises an amphiphilic branchedpolysiloxane prepolymer having UV-absorbing moieties and/or apolymerizable UV-absorbing agent, a benzoylphosphine oxidephotoinitiator is preferably used as the photoinitiator in theinvention. Preferred benzoylphosphine oxide photoinitiators includewithout limitation 2,4,6-trimethylbenzoyldiphenylophosphine oxide;bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; andbis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. It isunderstood that any photoinitiators other than benzoylphosphine oxideinitiators can be used in the invention.

Opening of the mold so that the molded lens can be removed from the moldmay take place in a manner known per se.

The molded contact lens can be subject to lens extraction to removeunpolymerized polymerizable components. The extraction solvent can beany solvent known to a person skilled in the art. Examples of suitableextraction solvent are those described above. After extraction, lensescan be hydrated in water or an aqueous solution of a wetting agent(e.g., a hydrophilic polymer).

The molded contact lenses can further subject to further processes, suchas, for example, surface treatment (for example, such as, plasmatreatment, chemical treatments, the grafting of hydrophilic monomers ormacromers onto the surface of a lens, Layer-by-layer coating, etc.);packaging in lens packages with a packaging solution which can containabout 0.005% to about 5% by weight of a wetting agent (e.g., ahydrophilic polymer described above) and/or a viscosity-enhancing agent(e.g., methyl cellulose (MC), ethyl cellulose, hydroxymethylcellulose,hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC),hydroxypropylmethyl cellulose (HPMC), or a mixture thereof);sterilization; and the like.

Preferred surfaces treatments are LbL coating such as those described inU.S. Pat. Nos. 6,451,871, 6,719,929, 6,793,973, 6,811,805, 6,896,926(herein incorporated by references in their entirety) and plasmatreatment. A preferred plasma treatment is those processes in which anionized gas is applied to the surface of an article as described in U.S.Pat. Nos. 4,312,575 and 4,632,844 (incorporated herein by reference intheir entireties).

A contact lens of the invention has an oxygen permeability of preferablyat least about 40 barrers, more preferably at least about 60 barrers,even more preferably at least about 80 barrers. In accordance with theinvention, an oxygen permeability is an apparent (directly measured whentesting a sample with a thickness of about 100 microns) oxygenpermeability according to procedures described in Examples.

A contact lens of the invention has an elastic modulus of about 2.0 MPaor less, preferably about 1.5 MPa or less, more preferably about 1.2 orless, even more preferably from about 0.4 MPa to about 1.0 MPa.

A contact lens of the invention further has an Ionoflux DiffusionCoefficient, D, of, preferably at least about 1.5×10⁻⁶ mm²/min, morepreferably at least about 2.6×10⁻⁶ mm²/min, even more preferably atleast about 6.4×10⁻⁶ mm²/min.

A contact lens of the invention further has a water content ofpreferably from about 15% to about 70%, more preferably from about 20%to about 50% by weight when fully hydrated. The water content of asilicone hydrogel contact lens can be measured according to BulkTechnique as disclosed in U.S. Pat. No. 5,849,811.

In a third aspect, the invention provides a silicone hydrogel contactlens obtained by the method of the invention.

In a fourth aspect, the invention provides a method for preparing anamphiphilic branched polysiloxane prepolymer, the method comprising thesteps of: (i) obtaining a partially ethylenically-functionalizedpolysiloxane, wherein the partially ethylenically-functionalizedpolysiloxane is a mixture of reaction products obtained by reacting afirst functionalizing vinylic monomer having a first reactive functionalgroup with a functional polysiloxane compound having two or more secondreactive functional groups at a molar equivalent ratio of from about 40%to about 95%, preferably from about 50% to about 95%, more preferablyfrom about 60% to about 92%, even more preferably from about 70% toabout 90% (the functionalizing vinylic monomer to the linearpolysiloxane compound), wherein each first reactive functional groupreacts with one second reactive functional group in the presence orabsence of a coupling agent to form a covalent bond or linkage, whereinthe mixture of reaction product comprises one or more polysiloxanevinylic monomers or macromers having at least one second reactivefunctional group and at least one ethylenically unsaturated group, oneor more polysiloxane crosslinkers having at least two ethylenicallyunsaturated groups, (ii) preparing a polymerizable compositioncomprising (a) the partially ethylenically-functionalized polysiloxane,(b) at least one hydrophilic vinylic monomer, (c) a chain transfer agentwhich is not a RAFT agent and optionally (but preferably) includes athird reactive functional group, and (d) a free-radical initiator; (ii)polymerizing the polymerizable composition to form an amphiphilicbranched polysiloxane copolymer comprising hydrophilic monomeric unitsderived from said at least one hydrophilic vinylic monomer, polysiloxanecrosslinking units derived from the polysiloxane crosslinkers, danglingpolysiloxane chains derived from the polysiloxane vinylic monomers ormacromers and each terminated with one second reactive functional group,and chain transfer units with or without third reactive functionalgroups; (iii) reacting the branched polysiloxane copolymer with a secondfunctionalizing vinylic monomer having a fourth reactive functionalgroup which reacts with one second or third reactive functional group ofthe branched polysiloxane copolymer in the presence or absence of acoupling agent to form a covalent linkage, thereby forming theamphiphilic branched polysiloxane prepolymer having danglingpolysiloxane chains each of which is terminated with oneethylenically-unsaturated group.

All of the various embodiments of the molds, lens-forming compositionsand components thereof, and spatial limitation of radiation, and contactlens of the invention described above for the first and second aspectsof the invention can be used in these two aspects of the invention.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. Various modifications, variations, andcombinations can be made to the various embodiment described herein. Inorder to better enable the reader to understand specific embodiments andthe advantages thereof, reference to the following examples issuggested. It is intended that the specification and examples beconsidered as exemplary.

Although various embodiments of the invention have been described usingspecific terms, devices, and methods, such description is forillustrative purposes only. The words used are words of descriptionrather than of limitation. It is to be understood that changes andvariations may be made by those skilled in the art without departingfrom the spirit or scope of the present invention, which is set forth inthe following claims. In addition, it should be understood that aspectsof the various embodiments may be interchanged either in whole or inpart or can be combined in any manner and/or used together. Therefore,the spirit and scope of the appended claims should not be limited to thedescription of the preferred versions contained therein.

EXAMPLE 1

Oxygen Permeability Measurements

The apparent oxygen permeability of a lens and oxygen transmissibilityof a lens material is determined according to a technique similar to theone described in U.S. Pat. No. 5,760,100 and in an article by Wintertonet al., (The Cornea: Transactions of the World Congress on the Cornea111, H. D. Cavanagh Ed., Raven Press: New York 1988, pp 273-280), bothof which are herein incorporated by reference in their entireties.Oxygen fluxes (J) are measured at 34° C. in a wet cell (i.e., gasstreams are maintained at about 100% relative humidity) using a Dk1000instrument (available from Applied Design and Development Co., Norcross,Ga.), or similar analytical instrument. An air stream, having a knownpercentage of oxygen (e.g., 21%), is passed across one side of the lensat a rate of about 10 to 20 cm³/min., while a nitrogen stream is passedon the opposite side of the lens at a rate of about 10 to 20 cm³/min. Asample is equilibrated in a test media (i.e., saline or distilled water)at the prescribed test temperature for at least 30 minutes prior tomeasurement but not more than 45 minutes. Any test media used as theoverlayer is equilibrated at the prescribed test temperature for atleast 30 minutes prior to measurement but not more than 45 minutes. Thestir motor's speed is set to 1200±50 rpm, corresponding to an indicatedsetting of 400±15 on the stepper motor controller. The barometricpressure surrounding the system, P_(measured), is measured. Thethickness (t) of the lens in the area being exposed for testing isdetermined by measuring about 10 locations with a Mitotoya micrometerVL-50, or similar instrument, and averaging the measurements. The oxygenconcentration in the nitrogen stream (i.e., oxygen which diffusesthrough the lens) is measured using the DK1000 instrument. The apparentoxygen permeability of the lens material, Dk_(app), is determined fromthe following formula:Dk _(app) =Jt/(P _(oxygen))where J=oxygen flux [microliters O₂/cm²−minute]

P_(oxygen)=(P_(measured)−P_(water)vapor)=(%O₂ in air stream) [mmHg]=partial pressure of oxygen in the air stream

P_(measured)=barometric pressure (mm Hg)

P_(water) vapor=0 mm Hg at 34° C. (in a dry cell) (mm Hg)

P_(water) vapor=40 mm Hg at 34° C. (in a wet cell) (mm Hg)

t=average thickness of the lens over the exposed test area (mm)

Dk_(app) is expressed in units of barrers.

The apparent oxygen transmissibility (Dk/t) of the material may becalculated by dividing the apparent oxygen permeability (Dk_(app)) bythe average thickness (t) of the lens.

The above described measurements are not corrected for the so-calledboundary layer effect which is attributable to the use of a water orsaline bath on top of the contact lens during the oxygen fluxmeasurement. The boundary layer effect causes the reported value for theapparent Dk (Dk_(app)) of a silicone hydrogel material to be lower thanthe actual intrinsic Dk value (Dk_(i)). Further, the relative impact ofthe boundary layer effect is greater for thinner lenses than withthicker lenses. The net effect is that the reported Dk appear to changeas a function of lens thickness when it should remain constant.

The intrinsic Dk value of a lens can be estimated based on a Dk valuecorrected for the surface resistance to oxygen flux caused by theboundary layer effect as follows.

Measure the apparent oxygen permeability values (single point) of thereference Iotrafilcon A (Focus® N&D® from CIBA VISION CORPORATION) orIotrafilcon B (AirOptix™ from CIBA VISION CORPORATION) lenses using thesame equipment. The reference lenses are of similar optical power as thetest lenses and are measured concurrently with the test lenses.

Measure the oxygen flux through a thickness series of Iotrafilcon A orIotrafilcon B (reference) lenses using the same equipment according tothe procedure for apparent Dk measurements described above, to obtainthe intrinsic Dk value (Dk_(i)) of the reference lens. A thicknessseries should cover a thickness range of approximately 100 μm or more.Preferably, the range of reference lens thicknesses will bracket thetest lens thicknesses. The Dk_(app) of these reference lenses must bemeasured on the same equipment as the test lenses and should ideally bemeasured contemporaneously with the test lenses. The equipment setup andmeasurement parameters should be held constant throughout theexperiment. The individual samples may be measured multiple times ifdesired.

Determine the residual oxygen resistance value, R_(r), from thereference lens results using equation 1 in the calculations.

$\begin{matrix}{R_{r} = \frac{\sum\left( {\frac{t_{j}}{{Dk}_{app}} - \frac{t_{j}}{{Dk}_{i}}} \right)}{n}} & (1)\end{matrix}$In which t is the thickness of a reference lens under measurement, and nis the number of the reference lenses measured. Plot the residual oxygenresistance value, R_(r) vs. t data and fit a curve of the form Y=a+bXwhere, for the jth lens, Y_(j)=(ΔP/J)_(j) and X=t_(j). The residualoxygen resistance, R_(r) is equal to a.

Use the residual oxygen resistance value determined above to calculatethe correct oxygen permeability Dk_(c) (estimated intrinsic Dk) for thetest lenses based on Equation 2.Dk _(c) =t/[(t/Dk _(a))−R _(r)]  (2)

The estimated intrinsic Dk of the test lens can be used to calculatewhat the apparent Dk (Dk_(a) _(_) _(std)) would have been for a standardthickness lens in the same test environment based on Equation 3.Dk _(a) _(_) _(std) =t _(std)/[(t _(std) /Dk _(c))+R _(r) _(_)_(std)]  (3)Ion Permeability Measurements. The ion permeability of a lens ismeasured according to procedures described in U.S. Pat. No. 5,760,100(herein incorporated by reference in its entirety. The values of ionpermeability reported in the following examples are relative ionofluxdiffusion coefficients (D/D_(ref)) in reference to a lens material,Alsacon, as reference material. Alsacon has an ionoflux diffusioncoefficient of 0.314×10⁻³ mm²/minute.Water Contact Angle (WCA) Measurements. Water contact angle (WCA)measurements are performed by the sessile drop method with a DSA 10 dropshape analysis system from Krüss GmbH, Germany with pure water (Fluka,surface tension 72.5 mN/m at 20° C.). For measurement purposes a contactlens is taken off the storage solution with tweezers and excess storagesolution is removed by gentle shaking. The contact lens are placed onthe male part of a lens mold and gently blotted with a dry and cleancloth. A water droplet (approximately 1 μl) is then dosed on the lensapex, and the change of the contact angle over time of this waterdroplet (WCA(t), circle fitting mode) is monitored. The WCA iscalculated by the extrapolation of the graph WCA(t) to t=0.UV-Absorbance. Contact lenses are manually placed into a speciallyfabricated sample holder or the like which can maintain the shape of thelens as it would be when placing onto eye. This holder is then submergedinto a 1 cm path-length quartz cell containing phosphate buffered saline(PBS, pH˜7.0-7.4) as the reference. A UV/visible spectrpohotmeter, suchas, Varian Cary 3E UV-Visible Spectrophotometer with a LabSphereDRA-CA-302 beam splitter or the like, can be used in this measurement.Percent transmission spectra are collected at a wavelength range of250-800 nm with % T values collected at 0.5 nm intervals. This data istransposed onto an Excel spreadsheet and used to determine if the lensesconform to Class 1 UV absorbance. UV absorbance is calculated using thefollowing equations:

${{UVA}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 380} - {316\mspace{14mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{20mu} T} \times 100}$${{UVB}\mspace{14mu}\%\mspace{14mu} T} = {\frac{{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 280} - {315\mspace{14mu}{nm}}}{{Luminescence}\mspace{14mu}\%\mspace{20mu} T} \times 100}$In which Luminescence % T is the average % transmission between 380 and780.Folding Mark Determination. A Contact Lens Optical Quality Analyzer(CLOQA) is developed to determine optical distortions caused by surfacedeformations and other defects in the contact lens, based on theprinciple of the Foucault knife-edge test. A person skilled in the artunderstands how to select, align and arrange various optics elements tocreate collimating light, to illuminate a contact lens, and to capturean image with a device (for example, such as, a CCD camera). The testinvolves illuminating the contact lens with a near-collimated light,placing a Foucault knife edge near the focal point, moving theknife-edge to block off most of the focused light, and capturing theimage of contact lens with a device, for example CCD camera behind theFoucault knife edge. Where there is no optical distortion in the contactlens, all light rays passing through the contact lens come to focus atthe knife edge and most of the well-focused light will be blocked off.For areas outside the optical zone which has no focusing function, theknife-edge will block the light from half of the lens to make it dark,while the other half appear bright. If the contact lens has no opticaldistortions in its optical zone, the whole optical zone will beuniformly dark or bright depending on how much light is blocked by theknife-edge. Where there are optical distortions on the contact lens,light passing through such areas in general does not fall into the mainfocus and may be either blocked by the knife edge (appearing dark) orpass through freely (appearing bright). The level of contrast not onlydepends on the amplitude of the distortion, but also depends on the fineposition of the knife-edge. The defective areas appear as contrastfeatures in the CLOQA image. The knife-edge test with CLOQA is designedas a qualitative testing device for optical distortions in the opticalzone.

Folding mark study is carried out as follows. Three autoclaved and/ornot autoclaved contact lenses are used in the study. First, images ofthe contact lenses are taken with the CLOQA. Second, each lens is foldedwith fingers twice (creating two perpendicular fold lines) and then itsimage is taken immediately with the CLOQA. Third, the image of eachcontact lens about 15 minutes after folding is taken with the CLOQA.Three types of CLOQA images are obtained: original one (i.e., withoutfolding), immediately after folding, and about 15 minutes after folding.The folding mark study allows to determine the appearance of the foldingline changing over time.

EXAMPLE 2

Various percent ethylenically-functionalized polysiloxanes are preparedas follows. KF-6001A(α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane, Mn=2000, fromShin-Etsu) and KF-6002A(α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane, Mn=3400, fromShin-Etsu) are separately dried at about 60° C. for 12 hours (orovernight) under high vacuum in a single neck flask. The OH molarequivalent weights of KF-6001A and KF-6002A are determined by titrationof hydroxyl groups and are used to calculate the milimolar equivalent tobe used in the synthesis.

A-1. Synthesis of Partially Ethylenically-Functionalized Polysiloxanes

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 75.00 g (75 meq) of driedKF6001A is charged to the reactor, and then 16.68 g (150 meq) of freshlydistilled isophorone diisocyanate (IPDI) is added into the reactor. Thereactor is purged with nitrogen and heated to 45° C. with stirring andthen 0.30 g of dibutyltin dilaurate (DBTDL) is added. The reactor issealed, and a positive flow of nitrogen is maintained. An exothermoccurs, after which the reaction mixture is allowed to cool and stir at55° C. for 2 hours. After reaching the exotherm, 248.00 g (150 meq) ofdried KF6002A is added to the reactor at 55° C. and then 100 μL of DBTDLis added. The reactor is stirred for four hours. Heating is discontinuedand the reactor is allowed to cool overnight. The nitrogen bubble isdiscontinued and the reactor is opened to atmosphere for 30 minutes withmoderate stirring. A hydroxyl-terminated polysiloxane having 3polysiloxane segments, HO-PDMS-IPDI-PDMS-IPDI-PDMS-OH, is formed.

For 80% ethylenically-functionalized polysiloxane, 18.64 g (120 meq) ofisocyanatoethyl methacrylate (IEM) is added to the reactor, along with100 μL of DBTDL. The reactor is stirred for 24 hours, and then productis decanted and stored under refrigeration. For preparation of variouspercentage of ethylenically functionalization of a polysiloxane, variousquantities of IEM are applied according following Table 1.

TABLE 1 % Ethylenical Functionalization of Polysiloxane Wt. of IEM A-1.160% 13.98 g (90 mEq) A-1.2 70% 16.31 g (105 meq) A-1.3 80% 18.64 g (120meq) A-1.4 100% 23.30 g (150 meq)A-2. 100% (Fully) Ethylenically Functionalized Polysiloxane:

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 75.00 g (75 meq) of driedKF6001A is charged to the reactor and dried at 60° C. under high vacuumfor 8 hours, and then 23.30 g (150 meq) of IEM is added to the reactorunder nitrogen. After 30 minutes of stirring, 0.2 g of DBTDL is added tothe mixture. The reactor is stirred at 25±3° C. for about 4 hours, andthen product is decanted and stored under refrigeration.

EXAMPLE 3

This example illustrates the effects of percentage ofethylenically-functionalization of polydisiloxane, which is used toprepare a prepolymer that in turn is used to prepare lens formulation,upon the viscosities of the lens formulations.

B-1. Synthesis of Amphiphilic Branched Copolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. 48.55 g of partiallyethylenically-functionalized polysiloxane (PDMS) prepared in Example 2,A-1.1 is charged to the reaction vessel. The PDMS A-1.1 is degassedunder vacuum less than 1 mbar at room temperature for 30 minutes. Afterthe degassed is accomplished, the reactor is filled with nitrogen gaswaiting for further process. The monomer solution composed of 26.06 g ofN,N-dimethylacrylamide (DMA), 23.14 g of(tris(trimethylsilyl))siloxypropyl)-acrylamide (TRIS-Am), and 350 g ofethyl acetate is charged to the 500-mL addition funnel followed with adegas under vacuum 100 mbar at room temperature for 10 minutes and thenrefilled with nitrogen gas. The monomer solution is degassed with sameconditions for additional two cycles. The monomer solution is thencharged to the reactor. The reaction mixture is heated to 64° C. withstirring. While heating, a solution composed of 1.75 g ofmercaptoethanol (chain transfer agent, CTA) and 0.30 g ofazoisobutyronitrile (Initiator) and 50 g of ethyl acetate is charged tothe addition funnel followed by same degassing process as the monomersolution. When the reactor temperature reaches 64° C., the initiator/CTAsolution is also added to reactor. The reaction is performed at 64° C.for 6 hours. After the copolymerization is completed, reactortemperature is cooled to room temperature.

B-2. Synthesis of Amphiphilic Branched Prepolymer

The copolymer solution prepared above (B-1) is ethylenicallyfunctionalized to form an amphiphilic branched prepolymer by adding 4.52g of IEM (or an amount shown in Table 2) and 0.15 g of DBTDL. Themixture is stirred at room temperature under a sealed condition for 12hours. The prepared prepolymer is then stabilized with 100 ppm ofhydroxy-tetramethylene piperonyloxy. After the reaction solvent isexchanged to 1-propanol, the solution is ready to be used forformulation. Various amphiphilic branched prepolymers are prepared withvarious combination of various % ethylenically-functionalizedpolysiloxane, CTA levels and IEM as indicated in Table 2.

TABLE 2 Amphiphilic Branched % ethylenically-functionalized Prepolymerpolysiloxane CTA % IEM B-2a Example 2, A-1.1 (60%) 1.75% 4.52 g B-2bExample 2, A-1.2 (70% 1.75% 4.35 g B-2c Example 2, A-1.3 (80%) 1.75%4.17 g B-2d Example 2, A-1.4 (100%) 1.75% 3.83 g B-2e Example 2, A-1.1(60%) 1.25% 3.43 g B-2f Example 2, A-1.2 (70% 1.25% 3.25 g B-2g Example2, A-1.3 (80%) 1.25% 3.08 gB-3: Preparation of Lens Formulations

Lens formulations are prepared by dissolving an amphiphilic branchedprepolymer prepared above (B-2a to B-2g) and other components shown inTable 3. Other ingredients in each formulation include 1.0% of DC1173(DAROCUR® 1173), 0.75% of DMPC(1,2-dimyristoyl-sn-glycero-3-phosphocholine) and 23.25% of 1-PrOH(1-propanol). Photorheologys of the prepared lens formulations arestudied by using UV irradiation with an intensity of 16 mW/cm² with 330nm filter (measured with ESE UV LOG) and also summarized in Table 3.

TABLE 3 Photorheology Lens Formulation Curing Amphiphilic Branched Time,G' Viscosity Prepolymer DMA TRIS-Am* seconds kPa mPa · s 65% of B-2a5.3% 4.7% 19 90 1020 65% of B-2b 5.3% 4.7% 17 100 1850 65% of B-2c 5.3%4.7% 16 110 2720 65% of B-2d 5.3% 4.7% 16 90 3150 65% of B-2e 5.3% 4.7%15 100 2100 65% of B-2f 5.3% 4.7% 14 105 3280 65% of B-2g 5.3% 4.7% 16105 5900 *(tris(trimethylsilyl))siloxypropyl)-acrylamide (TRIS-Am)

EXAMPLE 4

C-1: Synthesis of Amphiphilic Branched Copolymer

A 4-L jacketed reactor is equipped with overhead stirring, refluxcondenser with nitrogen/vacuum inlet adapter, thermometer, and samplingadapter. A mixture of 78.35 g of partially ethylenically-functionalizedpolysiloxane prepared in Example 2, A-1.3 and 8.71 g of Example 2, A-2is charged to the 4-L reactor and then degassed under vacuum less than10 mbar at room temperature for 30 minutes. After the degassing, thereactor is filled with nitrogen gas waiting for further process. Themonomer solution composed of 52.51 g of DMA, 56.65 g of TRIS-Am and 390g of cyclohexane is transferred to the reactor. The final mixture isdegassed at 100 mbar for 5 minutes and then refilled with nitrogen gas.This degas cycle is repeated for 4 more times. The reaction mixture isthen heated to 64° C. followed by adding a degassedinitiator/chain-transfer-agent solution composed of 0.60 g of V-601(Dimethyl 2,2′-azobis(2-methylpropionate, from WAKO SpecialtyChemicals), 7.50 g of mercaptoethanol (CTA) and 10 g of THF. Thecopolymerization is performed at 64° C. under nitrogen for totally 6hours. After reaction is finished, reactor temperature is cooled to roomtemperature.

C-2. Synthesis of Amiphiphilic Branched Prepolymer

The copolymer solution prepared above (C−1) is ethylenicallyfunctionalized to form an amphiphilic branched prepolymer by adding 7.50g of IEM and 0.21 g of DBTDL, followed by an agitation under a sealeddry condition at room temperature for 48 hours. The prepared prepolymeris then stabilized with 100 ppm of hydroxy-tetramethylene piperonyloxy.After a repeated processes of evaporation of the reaction solvent andaddition of 1-propanol are carried out to replace the reaction solventwith to 1-propanol, the solution is ready to be used for formulation.

C-3: Preparation of Lens Formulations and Photorheology

The amphiphilic branched prepolymer prepared above (C-3) is formulatedwith final compositions listed in Table 4. Photorheology of preparedformulations is studied by using UV irradiation with intensity 16 mW/cm²with 330 nm filter.

TABLE 4 Photorheology Formulation Curing Viscosity Lot# C-2 DMA DC1173DMPC 1-PrOH Time (s) G′ kPa mPa · s C-3.1 69% 6% 1.0% 0.75% 23.25% 19115 3200 C-3.2 70% 5% 1.0% 0.75% 23.25% 21 114 3400 DMPC:1,2-dimyristoyl-sn-glycero-3-phosphocholine; DC1173: Darocur 1173C-4: Lens Preparation and Characterization

Contact lenses are prepared by cast-molding from a lens formulationprepared above (C-3.1 and C-3.2) in a reusable mold, similar to the moldshown in FIGS. 1-6 in U.S. Pat. Nos. 7,384,590 and 7,387,759 (FIGS.1-6). The mold comprises a female mold half made of CaF₂ and a male moldhalf made of PMMA. The UV irradiation source is a Hamamatsu lamp withthe WG335+TM297 cut off filter at an intensity of about 4 mW/cm²(measured with ESE UV LOG). The lens formulation in the mold isirradiated with UV irradition for about 25 seconds. Prepared lenses areextracted with isopropanol, rinsed in pure water, coated withpolyacrylic acid (PAA) (M.W.: 450 kDa, from Lubrizol) by dipping lensesin a 1-PrOH solution of PAA (0.1% by weight, pH 2.5), and then hydratedwith pure water. The coated lenses are packaged in lens packagescontaining phosphate buffered saline and autoclaved. The oxygenpermeability (Dk_(app) and Dk_(c)) and ion permeability (IP) aredetermined according to the procedures described in Example 1. Theproperties, Dk (barrers), IP (relative to Alsacon), elastic modulus(E′), elongation at break (EtB), and water content (% by weight) of thelenses are reported in Table 5.

TABLE 5 Lot# E′ (MPa) EtB (%) Dk_(app) Dk_(C) ^(#) IP Water % C-3.1 0.68260% 83¹ 136 5.1 34.0% C-3.2 0.67 260% 86² 143 4.2 31.9% ¹Average lenscenter thickness: 113 μm. ²Average lens center thickness: 115 μm.^(#)Lotrafilcon B lenses with an average lens center thickness of 80 μmis used as reference lenses and the intrinsic Dk of the reference lensesis 110 barrers.

EXAMPLE 5

D-1. Synthesis of Amphiphilic Branched Copolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. 45.60 g of partiallyethylenically-functionalized polysiloxane prepared in Example 2, A-1.3is charged to the reaction vessel and then degassed under vacuum lessthan 1 mbar at room temperature for 30 minutes. After the degassing,reactor is filled with nitrogen gas waiting for further process. Themonomer solution composed of 0.65 g of hydroxyethyl methacrylate (HEMA),25.80 g of DMA, 27.80 g of 3-[Tris(trimethylsiloxy)silyl]propylmethacrylate (TRIS), and 279 g of ethyl acetate is charged to the 500-mLaddition funnel followed with a degas under vacuum 100 mbar at roomtemperature for 10 minutes and then refilled with nitrogen gas. Themonomer solution is degassed with same conditions for additional twocycles. The monomer solution is then charged to the reactor. Thereaction mixture is heated to 67° C. with stirring. While heating, asolution composed of 1.50 g of mercaptoethanol (CTA) and 0.26 g ofazoisobutyronitrile(initiator) and 39 g of ethyl acetate is charged tothe addition funnel followed by same degas process as the monomersolution. When the reactor temperature reaches 67° C., the initiator/CTAsolution is also added to reactor. The reaction is performed at 67° C.for 8 hours. After the copolymerization is completed, reactortemperature is cooled to room temperature.

D-2. Synthesis of Amiphiphilic Branched Prepolymer

The copolymer solution prepared above (D−1) is ethylenicallyfunctionalized to form an amphiphilic branched prepolymer by adding 4.45g of IEM (or isocyanatoethyl methacrylate in a desired molar equivalentamount) in the presence of 0.21 g of DBTDL. The mixture is stirred atroom temperature under a sealed condition for 24 hours. The preparedmacromonomer is then stabilized with 100 ppm of hydroxy-tetramethylenepiperonyloxy before the solution is concentrated to 200 g (˜50%) andfiltered through 1 μm pore size filter paper. The solid content ismeasured via removing the solvent in vacuum oven at 80° C. After thereaction solvent is exchanged to 1-propanol, the solution is furtherconcentrated to the desired concentration and ready to be used forpreparing lens formulations.

D-3. Preparation of Lens Formulation and Photorheology

A lens formulation is prepared to have the following composition: 72% byweight of prepolymer D2 prepared above; 6% by weight of DMA; 1% byweight of DC1173; 0.75% by weight of DMPC; and 20.25% by weight of1-PrOH. Photo-rheology is studied by using the Hamamatsu lamp with a 330nm long pass cutoff filter placed just before the sample. The intensity(16 mW/cm²) is measured by using ESE UV LOG with a 297 nm cutoff filter,the long pass filters are place before the sample for curing theformulation. The results of photorheology study are: a curing time ofabout 12 seconds, G′ of 165 kPa, and a viscosity of 5550 mPa·s.

D-4: Lens Characterization

Contact lenses are cast-molded from lens formulation D3, extracted withisopropanol, rinsed in water, coated with PAA, hydrated in water,packaged/autoclaved in lens packages, and characterized according to theprocedures described in Example 4. The obtained lenses have thefollowing properties: E′=0.75 MPa; EtB %=212; Dk_(app)=95 (for lenseswith an average center thickness of 119 μm); DK_(c)=172 (usingIotrafilcon B lenses as reference lenses, an average center thickness of81 μm and an intrinsic Dk 110); IP=3.6; water %=29.0.

EXAMPLE 6

E-1: Synthesis of UV-Absorbing Amphiphilic Branched Copolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. 45.98 g of partially ethylenicallyfunctionalized polysiloxane prepared in Example 2, A-1.3 is charged tothe reaction flask and then degassed under vacuum less than 1 mbar atroom temperature for about 30 minutes. The monomer solution prepared bymixing 0.51 g of HEMA, 25.35 g of DMA, 1.38 g of Norbloc methacrylate,26.03 g of TRIS, and 263 g of ethyl acetate is charged to the 500-mLaddition funnel followed with a degas under vacuum 100 mbar at roomtemperature for 10 minutes and then refilled with nitrogen gas. Themonomer solution is degassed with same conditions for additional twocycles. The monomer solution is then charged to the reactor. Thereaction mixture is heated to 67° C. with adequate stirring. Whileheating, a solution composed of 1.48 g of mercaptoethanol (chaintransfer agent, CTA) and 0.26 g of azoisobutyronitrile(initiator) and 38g of ethyl acetate is charged to the addition funnel followed by samedegas process as the monomer solution. When the reactor temperaturereaches 67° C., the initiator/CTA solution is also added to reactor. Thereaction is performed at 67° C. for 8 hours. After the copolymerizationis completed, reactor temperature is cooled to room temperature.

E-2: Synthesis of UV-absorbing Amphiphilic Branched Prepolymer

The copolymer solution prepared above (E−1) is ethylenicallyfunctionalized to form an amphiphilic branched prepolymer by adding 3.84g of IEM (or isocyanatoethyl methacrylate in a desired molar equivalentamount) in the presence of 0.15 g of DBTDL. The mixture is stirred atroom temperature under a sealed condition for 24 hours. The preparedprepolymer is then stabilized with 100 ppm of hydroxy-tetramethylenepiperonyloxy before the solution is concentrated to 200 g (˜50%) andfiltered through 1 um pore size filter paper. After the reaction solventis exchanged to 1-propanol through repeated cycles of evaporation anddilution, the solution is ready to be used for formulation. The solidcontent is measured via removing the solvent at vacuum oven at 80° C.

E-3: Preparation of Lens Formulation and Photorheology

A lens formulation is prepared to have the following composition: 71% byweight of prepolymer E2 prepared above; 4% by weight of DMA; 1% byweight of TPO; 0.75% by weight of DMPC; and 23.25% by weight of 1-PrOH.Photo-rheology is studied by using the Hamamatsu lamp with a stack of330 nm and 388 nm long pass cutoff filters placed just before thesample. The intensity (4.6 mW/cm²) is measured by using an IL1700detector using a SED005 sensor with a 297 nm cutoff filter fromInternational light, the long pass filters are placed before the samplefor curing the formulation. The results of photorheology study are: acuring time of about 22 seconds, G′ of 155 kPa, and a viscosity of 2900mPa·s.

E-4: Lens Characterization

Contact lenses are cast-molded from lens formulation E3, extracted withisopropanol, rinsed in water, coated with PAA, hydrated in water,packaged/autoclaved in lens packages, and characterized according to theprocedures described in Example 4. The obtained lenses have thefollowing properties: E′=0.72 MPa; EtB %=130; Dk_(app)=101 (for lenseswith an average center thickness of 122 μm); DK_(c)=181 (usingIotrafilcon B as reference lenses, an average center thickness of 80 μmand an intrinsic Dk 110); IP=2.9; water %=26.9; and UVA/UVB %T=4.310.09.

EXAMPLE 7

A: Synthesis of 80% Ethylenically-Functionalized Chain-extendedPolysiloxane

KF-6001A (α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane, Mn=2000,from Shin-Etsu) and KF-6002A(α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane, Mn=3400, fromShin-Etsu) are separately dried at about 60° C. for 12 hours (orovernight) under high vacuum in a single neck flask. The OH molarequivalent weights of KF-6001A and KF-6002A are determined by titrationof hydroxyl groups and are used to calculate the millimolar equivalentto be used in the synthesis.

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 75.00 g (75 meq) of driedKF6001A is charged to the reactor, and then 16.68 g (150 meq) of freshlydistilled IPDI is added into the reactor. The reactor is purged withnitrogen and heated to 45° C. with stirring and then 0.30 g of DBTDL isadded. The reactor is sealed, and a positive flow of nitrogen ismaintained. An exotherm occurs, after which the reaction mixture isallowed to cool and stir at 55° C. for 2 hours. After reaching theexotherm, 248.00 g (150 meq) of dried KF6002A is added to the reactor at55° C. and then 100 μl of DBTDL is added. The reactor is stirred forfour hours. Heating is discontinued and the reactor is allowed to coolovernight. The nitrogen bubble is discontinued and the reactor is openedto atmosphere for 30 minutes with moderate stirring. Ahydroxyl-terminated chain-extended polysiloxane having 3 polysiloxanesegments, HO-PDMS-IPDI-PDMS-IPDI-PDMS-OH (or HO-CE-PDMS-OH), is formed.

For 80% ethylenically-functionalized polysiloxane, 18.64 g (120 meq) ofIEM is added to the reactor, along with 100 μL of DBTDL. The reactor isstirred for 24 hours, and then product (80% IEM-capped CE-PDMS) isdecanted and stored under refrigeration.

B: Synthesis of Non-UV-absorbing Amphiphilic Branched PolysiloxanePrepolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. The reactor is charged with 45.6 g of80% IEM-capped CE-PDMS prepared above and sealed. A solution of 0.65 gof hydroxyethyl methacrylate (HEMA), 25.80 g of DMA, 27.80 g of(tris(trimethylsilyl))-siloxypropyl)methacrylate (TRIS), in 279 g ofethyl acetate is charged to the addition funnel. The reactor is degassedat <1 mbar for 30 minutes at RT with a high-vacuum pump. The monomersolution is degassed at 100 mbar and RT for 10 minutes for three cycles,breaking vacuum with nitrogen between degas cycles. The monomer solutionis then charged to the reactor, and then the reaction mixture is stirredand heated to 67° C. While heating, a solution of 1.50 g ofmercaptoethanol (chain transfer agent, CTA) and 0.26 g ofazoisobutyronitrile dissolved in 39 g of ethyl acetate is charged to theaddition funnel and deoxygenated three times at 100 mbar, RT for 10minutes. When the reactor temperature reaches 67° C., the initiator/CTAsolution is added to the PDMS/monomer solution in the reactor. Thereaction is allowed to proceed for 8 hours, and then heating isdiscontinued and reactor temperature is brought to room temperaturewithin 15 minutes.

The resultant reaction mixture then is siphoned to a dry single-neckflask with airtight lid, and 4.452 g of IEM is added with 0.21 g ofDBTDL. The mixture is stirred 24 hs at room temperature, formingnon-UV-absorbing amphiphilic branched polysiloxane prepolymer. To thismixture solution, 100 uL of hydroxy-tetramethylene piperonyloxy solutionin ethyl acetate (2 g/20 mL) is added. The solution is then concentratedto 200 g (˜50%) using rota-yap at 30° C. and filtered through 1 um poresize filter paper. After solvent exchange to 1-propanol, the solution isfurther concentrated to the desired concentration.

C. Synthesis of UV-absorbing Amphiphilic Branched PolysiloxanePrepolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. The reactor is then charged with45.98 g of 80% IEM-capped CE-PDMS prepared above and the reactor issealed. A solution of 0.512 g of HEMA, 25.354 g of DMA, 1.38 g ofNorbloc methacrylate, 26.034 g of TRIS, in 263 g of ethyl acetate ischarged to the addition funnel. The reactor is degassed at <1 mbar for30 minutes at RT with a high-vacuum pump. The monomer solution isdegassed at 100 mbar and RT for 10 minutes for three cycles, breakingvacuum with nitrogen between degas cycles. The monomer solution is thencharged to the reactor, and then the reaction mixture is stirred andheated to 67° C. While heating, a solution of 1.480 g of mercaptoethanol(chain transfer agent, CTA) and 0.260 g of azoisobutyronitrile dissolvedin 38 g of ethyl acetate is charged to the addition funnel anddeoxygenated three times at 100 mbar, room temperature for 10 minutes.When the reactor temperature reaches 67° C., the initiator/CTA solutionis added to the PDMS/monomer solution in the reactor. The reaction isallowed to proceed for 8 hours, and then heating is discontinued andreactor temperature is brought to room temperature within 15 min.

The resultant reaction mixture then is siphoned to a dry single-neckflask with airtight lid, and 3.841 g of isocyanatoethyl acrylate isadded with 0.15 g of DBTDL. The mixture is stirred 24 hs at roomtemperature, forming a UV-absorbing amphiphilic branched polysiloxaneprepolymer. To this mixture solution, 100 uL of hydroxy-tetramethylenepiperonyloxy solution in ethyl acetate (2 g/20 mL) is added. Thesolution is then concentrated to 200 g (˜50%) using rota-yap at 30° C.and filtered through 1 um pore size filter paper.

D-1: Lens Formulation with Non-UV-absorbing Polysiloxane Prepolymer

In a 100 mL amber flask, 4.31 g of macromer solution (which is asolution of 82.39% in 1-propanol, prepared from the macromer solutionprepared above by repeated cycles of evaporation of 1-propanol dilutionof) is added. In a 20 mL vial, 0.081 g of TPO and 0.045 g of DMPC aredissolved in 10 g of 1-propanol and then transferred to the macromersolution. After the mixture is concentrated to 5.64 g using rota-yap at30° C., 0.36 g of DMA is added and the formulation is homogenized atroom temperature. 6 g of clear lens formulation D-1 is obtained.

D-2: Lens Formulation with UV-absorbing Polysiloxane Prepolymer (4% DMA)

In a 100 mL amber flask, 24.250 g of macromer solution (43.92% in ethylacetate) is added. In a 50 mL vial, 0.15 g of TPO and 0.75 g of DMPC isdissolved in 20 g of 1-propanol and then transferred to the macromersolution. 20 g of solvent is pulled off using rota-yap at 30° C.,followed by addition of 20 g of 1-propanol. After two cycles, themixture is concentrated to 14.40 g. 0.6 g of DMA is added to thismixture and the formulation is homogenized at room temperature. 15 g ofclear lens formulation D-2 is obtained.

D-3: Lens Formulation with UV-absorbing Polysiloxane Prepolymer (2%DMA/2% HEA)

In a 100 mL amber flask, 24.250 g of macromer solution (43.92% in ethylacetate) is added. In a 50 mL vial, 0.15 g of TPO and 0.75 g of DMPC isdissolved in 20 g of 1-propanol and then transferred to the macromersolution. 20 g of solvent is pulled off using rota-yap at 30° C.,followed by addition of 20 g of 1-propanol. After two cycles, themixture is concentrated to 14.40 g. 0.3 g of DMA and 0.3 g of HEA isadded to this mixture and the formulation is homogenized at roomtemperature. 15 g of clear lens formulation D-3 is obtained.

EXAMPLE 8

E: Covalent Attachment of Modified PAE Coating Polymers

Monomers containing amine groups, N-(3-Aminopropyl)methacrylamidehydrochloride (APMAA-HCl) or N-(2-aminoethyl) methacrylamidehydrochloride (AEMAA-HCl) are purchased from Polysciences and used asreceived. Poly(amidoamine epichlorohydrine) (PAE) is received fromAshland as an aqueous solution and used as received.Poly(acrylamide-co-acrylic acid) (poly(AAm-co-AA) (90/10) fromPolysciences, mPEG-SH from Laysan Bio, and poly(MPC-co-AeMA) (i.e., acopolymer of methacryloyloxyethyl phosphorylcholine (MPC) andaminoethylmethacrylate (AeMA)) from NOF are used as received.

APMAA-HCl monomer is dissolved in methanol and added to the lensformulations D-1, D-2 and D-3 (prepared in Example 7) to achieve a 1 wt% concentration.

Reactive packaging saline is prepared by dissolving the componentslisted in Table 6 along with appropriate buffer salts in DI water. Afterheated pre-treatment, the saline is allowed to cool to room temperatureand then filtered using a 0.2 μm PES filter.

TABLE 6 Package Saline Sample 1 2 3 4 5 pH 7.4 7.4 7.4 8 8 PAE  0.2%0.2% 0.2% 0.2% 0.2% Poly(AAm-co-AA) (90/10) 0.07% 0.2% — — — mPEG-SH, Mw= 2000 — — 0.3% — — mPEG-SH, Mw = 10000 — — — 0.2% — Poly(MPC-Co-AeMA)(90/10) — — — — 0.2% Pre-reaction condition 70° C., 4 h 70° C., 4 h 45°C., 4 h 45° C., 4 h 65° C., 2 h

Lens formulation D-1, D-2 and D3 prepared in Example 7 is modified byaddition of the APMAA-HCl monomer (stock solution of APMMA-HCL inmethanol). DSM lens is cured at 16 mW/cm² with 330 nm filter while LSlens is cured at 4.6 mW/cm² with 380 nm filter.

DSM lenses. Female portions of polypropylene lens molds are filled withabout 75 microliters of a lens formulation prepared as above, and themolds are closed with the male portion of the polypropylene lens molds(base curve molds). Contact lenses are obtained by curing the closedmolds for about 5 minutes with an UV irradiation source (Hamamatsu lampwith a 330 nm-cut-off filter at an intensity of about 16 mW/cm².

LS lenses. LS lenses are prepared by cast-molding from a lensformulation prepared as above in a reusable mold, similar to the moldshown in FIGS. 1-6 in U.S. Pat. Nos. 7,384,590 and 7,387,759 (FIGS.1-6). The mold comprises a female mold half made of quartz (or CaF₂) anda male mold half made of glass (or PMMA). The UV irradiation source is aHamamatsu lamp with a 380 nm-cut-off filter at an intensity of about 4.6mW/cm². The lens formulation in the mold is irradiated with UVirradiation for about 30 seconds.

Lens formulation D-1 (of Example 7) modified with APMAA-HCl is curedaccording to DSM and LS methods described above, while with lensformulation D-2 or D-3 (of Example 7) is cured according to the LSmethod described above.

Molded lenses are extracted in methyl ethyl ketone, hydrated, andpackaged in one of the salines described in Table 6. Lenses are placedin a polypropylene lens packaging shell with 0.6 mL of the IPC saline(half of the saline is added prior to inserting the lens). The blisteris then sealed with foil and autoclaved for 30 min at 121° C.

Evaluation of the lens surface shows that all test lenses had no debrisadhesion. When observed under dark-field microscope, cracking lines arenot visible after rubbing the lenses between the fingers.

The lens surface wettability (WBUT), lubricity, and contact angle aremeasured and results are summarized in Table 7.

TABLE 7 Lens formulation for Contact making lenses Saline¹ WBUT (second)Lubricity Angle [°] D1 as control 1 0 4-5 114 (free of APMAA) 3 0 4 119D1 w/1% APMAA 1 10  0-1 104 3 2 0-1  99 D2 as control 1 0 4-5 115 (freeof APMAA) 3 0 3 107 4  0²  3-4²  116² D2 w/1% APMAA 1 5 2-3  90 3 6 1 95 4 5-10²  3²  106² D3 as control 1  1²  3-4²  105² (free of APMAA) 2 5²  3-4²   94² 3  0²  3²  112² 4  12²   3²   36² 5  4²  3²  102² D3w/1% APMAA 1  0²  4²  103² 2  9²  3-4²   97² 3  14²   2-3²   91² 4  15²  3²   54² 5  13²   2²   69² ¹The number is the packaging saline numbershown in Table 5. ²LS lenses.

The tested lenses are made according DSM method unless specifiedotherwise. Lubricity is rated against a qualitative scale from 0 to 4where lower numbers indicate greater lubricity. In general, lens surfaceproperties are somewhat improved after application of the in-packagecoating.

EXAMPLE 9

Lenses are fabricated using lens formulation D-2 (Example 7) to whichAPMAA monomer has been added to a concentration of 1%. LS lenses areprepared by cast-molding from a lens formulation prepared as above in areusable mold, similar to the mold shown in FIGS. 1-6 in U.S. Pat. Nos.7,384,590 and 7,387,759 (FIGS. 1-6). The mold comprises a female moldhalf made of glass and a male mold half made of quartz. The UVirradiation source is a Hamamatsu lamp with a 380 nm-cut-off filter atan intensity of about 4.6 mW/cm². The lens formulation in the mold isirradiated with UV irradiation for about 30 seconds.

Cast-molded lenses are extracted with methyl ethyl ketone (MEK), rinsedin water, coated with polyacrylic acid (PAA) by dipping lenses in apropanol solution of PAA (0.0044% by weight, acidified with formic acidto about pH 2.5), and hydrated in water.

IPC Saline is prepared from a composition containing about 0.07%PAAm-PAA and sufficient PAE to provide an initial azetidinium content ofapproximately 8.8 millimole equivalents/Liter (˜0.15% PAE) underpre-reaction conditions of 8 hrs at approximately 60° C. 10 ppm hydrogenperoxide is then added to the IPC salines to prevent bioburden growthand the IPC salines are filtered using a 0.22 micron polyether sulphone[PES] membrane filter Lenses are placed in a polypropylene lenspackaging shell with 0.6 mL of the IPC saline (half of the saline isadded prior to inserting the lens). The blister is then sealed with foiland autoclaved for 30 min at 121° C.

Evaluation of the lens surface shows that all test lenses have no debrisadhesion. When observed under dark-field microscope, cracking lines arenot visible after rubbing the lenses between the fingers. The lenssurface wettability (WBUT) is greater than 10 seconds, lubricity israted as “1”, and contact angle is approximately 20°.

EXAMPLE 10

Synthesis of UV-absorbing Amphiphilic Branched Copolymer

A 1-L jacketed reactor is equipped with 500-mL addition funnel, overheadstirring, reflux condenser with nitrogen/vacuum inlet adapter,thermometer, and sampling adapter. 89.95 g of partially ethylenicallyfunctionalized polysiloxane prepared in Example 2, A-1.3 is charged tothe reactor and then degassed under vacuum less than 1 mbar at roomtemperature for about 30 minutes. The monomer solution prepared bymixing 1.03 g of HEMA, 50.73 g of DMA, 2.76 g of Norbloc methacrylate,52.07 g of TRIS, and 526.05 g of ethyl acetate is charged to the 500-mLaddition funnel followed with a degas under vacuum 100 mbar at roomtemperature for 10 minutes and then refilled with nitrogen gas. Themonomer solution is degassed with same conditions for additional twocycles. The monomer solution is then charged to the reactor. Thereaction mixture is heated to 67° C. with adequate stirring. Whileheating, a solution composed of 2.96 g of mercaptoethanol (chaintransfer agent, CTA) and 0.72 g of dimethyl2,2′-azobis(2-methylpropionate) (V-601-initiator) and 76.90 g of ethylacetate is charged to the addition funnel followed by same degas processas the monomer solution. When the reactor temperature reaches 67° C.,the initiator/CTA solution is also added to reactor. The reaction isperformed at 67° C. for 8 hours. After the copolymerization iscompleted, reactor temperature is cooled to room temperature.

Synthesis of UV-absorbing Amphiphilic Branched Prepolymer

The copolymer solution prepared above is ethylenically functionalized toform an amphiphilic branched prepolymer by adding 8.44 g of IEM (or2-isocyanatoethyl methacrylate in a desired molar equivalent amount) inthe presence of 0.50 g of DBTDL. The mixture is stirred at roomtemperature under a sealed condition for 24 hours. The preparedprepolymer is then stabilized with 100 ppm of hydroxy-tetramethylenepiperonyloxy before the solution is concentrated to 200 g (˜50%) andfiltered through 1 um pore size filter paper. After the reaction solventis exchanged to 1-propanol through repeated cycles of evaporation anddilution, the solution is ready to be used for formulation. The solidcontent is measured via removing the solvent at vacuum oven at 80° C.

Preparation of Lens Formulation

A lens formulation is prepared to have the following composition: 71% byweight of prepolymer prepared above; 4% by weight of DMA; 1% by weightof TPO; 1% by weight of DMPC; 1% by weight of Brij 52 (from), and 22% byweight of 1-PrOH.

Lens Preparation

Lenses are fabricated by cast-molding of the lens formulation preparedabove using reusable mold, similar to the mold shown in FIGS. 1-6 inU.S. Pat. Nos. 7,384,590 and 7,387,759 (FIGS. 1-6) under spatiallimitation of UV irradiation. The mold comprises a female mold half madeof glass and a male mold half made of quartz. The UV irradiation sourceis a Hamamatsu lamp with a 380 nm-cut-off filter at an intensity ofabout 4.6 mW/cm². The lens formulation in the mold is irradiated with UVirradiation for about 30 seconds.

Cast-molded lenses are extracted with methyl ethyl ketone (MEK), rinsedin water, coated with polyacrylic acid (PAA) by dipping lenses in apropanol solution of PAA (0.004% by weight, acidified with formic acidto about pH 2.0), and hydrated in water.

IPC Saline is prepared from a composition containing about 0.07%PAAm-PAA and sufficient PAE to provide an initial azetidinium content ofapproximately 8.8 millimole equivalents/Liter (˜0.15% PAE) underpre-reaction conditions of 6 hrs at approximately 60° C. 5 ppm hydrogenperoxide is then added to the IPC salines to prevent bioburden growthand the IPC salines are filtered using a 0.22 micron polyether sulphone[PES] membrane filter Lenses are placed in a polypropylene lenspackaging shell with 0.6 mL of the IPC saline (half of the saline isadded prior to inserting the lens). The blister is then sealed with foiland autoclaved for 30 min at 121° C.

Lens Characterization

The obtained lenses have the following properties: E′˜0.82 MPa;DK_(c)˜159.4 (using Iotrafilcon B as reference lenses, an average centerthickness of 80 μm and an intrinsic Dk 110); IP˜2.3; water %˜26.9; andUVA/UVB % T˜4.6/0.1.

What is claimed is:
 1. A silicone hydrogel contact lens comprising apolymeric material which is a polymerization product of a lens-formingcomposition including: (1) an amphiphilic branched polysiloxaneprepolymer, wherein the amphiphilic branched polysiloxane prepolymer isobtained by (i) polymerizing a polymerizable composition to obtain amixture of amphiphilic branched polysiloxane copolymer, wherein thepolymerizable composition comprises (a) a partiallyethylenically-functionalized polysiloxane, wherein the partiallyethylenically-functionalized polysiloxane is a mixture of reactionproducts obtained by reacting a first ethylenically functionalizingvinylic monomer having a first reactive functional group with afunctional polysiloxane compound having two or more second reactivefunctional groups at a molar equivalent ratio, R_(Equivalent), of fromabout 40% to about 95%, wherein each first reactive functional groupreacts with one second reactive functional group in the presence orabsence of a coupling agent to form a covalent bond or linkage, whereinthe mixture of reaction product comprises at least one polysiloxanecrosslinkers having at least two ethylenically unsaturated groups and atleast one polysiloxane vinylic monomer or macromer having at least onesecond reactive functional group and at least one ethylenicallyunsaturated group, (b) at least one hydrophilic vinylic monomer, (c)optionally a hydrophobic vinylic monomer, (d) a chain transfer agentother than a RAFT agent, wherein the chain transfer agent optionallyincluding a third reactive functional group, and (e) a free-radicalinitiator, and (ii) ethylenically functionalizing the amphiphilicbranched polysiloxane copolymer by reacting it with a secondethylenically functionalizing vinylic monomer having a fourth reactivefunctional group which reacts with one second or third reactivefunctional group in the presence or absence of a coupling agent to forma covalent linkage, thereby forming the amphiphilic branchedpolysiloxane prepolymer; and (2) less than 20% by weight of one or morevinylic monomers relative to the total amount of all polymerizablecomponents in the lens-forming composition; and (3) optionally ahydrophobic vinylic monomer.
 2. The silicone hydrogel contact lens ofclaim 1, wherein the lens-forming composition comprises: from about 75%to about 97% by weight of the amphiphilic branched polysiloxaneprepolymer; from about 0.1% to about 5% by weight of a free-radicalinitiator; and from about 2% to about 16% by weight of said one or morevinylic monomers, wherein the percentages by weight of the componentslisted above are relative to the total amount of all polymerizablecomponents including those not listed above in the lens-formingcomposition.
 3. The silicone hydrogel contact lens of claim 2, whereinthe polymerizable composition comprising: (a) from about 20% to about80% by weight of the partially ethylenically-functionalizedpolysiloxane; (b) from about 5% to about 75% by weight of at least onehydrophilic vinylic monomer; (c) from 0 to about 55% by weight of abulky hydrophobic vinylic monomer; (d) from about 0.25% to about 5% byweight of a chain transfer agent other than a RAFT agent, wherein thechain transfer agent optionally including a reactive functional group;(e) from 0 to 5% by weight by weight of a polymerizable UV-absorbingcompound; and (f) from about 0.1% to about 5% by weight of a freeradical initiator, wherein the percentages by weight of the above-listedcomponents are relative to the combined weight of all polymerizablecomponents.
 4. The silicone hydrogel contact lens of claim 3, whereinthe hydrophilic vinylic monomer in the polymerizable composition is freeof reactive functional group capable of participating in a couplingreaction with the second ethylenically functionalizing vinylic monomer.5. The silicone hydrogel contact lens of claim 3, wherein thepolymerizable composition comprises a first hydrophilic vinylic monomerfree of any reactive functional group capable of participating in acoupling reaction with the second ethylenically functionalizing vinylicmonomer and a second hydrophilic vinylic monomer having a reactivefunctional group capable of participating the coupling reaction with thesecond ethylenically functionalizing vinylic monomer, wherein the firstand second hydrophilic vinylic monomers are present in the polymerizablecomposition at a ratio of from about 5:1 to about 30:1.
 6. The siliconehydrogel contact lens of claim 5, wherein the first hydrophilic vinylicmonomer is selected from the group consisting of N,N-dimethyl(meth)acrylamide, N-methyl-3-methylene-2-pyrrolidone,1-ethyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone,1-ethyl-5-methylene-2-pyrrolidone, 5-methyl-3-methylene-2-pyrrolidone,5-ethyl-3-methylene-2-pyrrolidone, 1-n-propyl-3-methylene-2-pyrrolidone,1-n-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone,1-n-butyl-3-methylene-2-pyrrolidone,1-tert-butyl-3-methylene-2-pyrrolidone, dimethylaminoethyl(meth)acrylate, N-vinyl-2-pyrrolidone, a C₁-C₄-alkoxy polyethyleneglycol (meth)acrylate, N-vinyl formamide, N-vinyl acetamide, N-vinylisopropylamide, N-vinyl-N-methyl acetamide, and mixtures thereof; andwherein the second hydrophilic vinylic monomer is selected from thegroup consisting of hydroxyl-substituted C₁-C₄ alkyl (meth)acrylate,hydroxyl-substituted C₁-C₄ alkyl (meth)acrylamide, amino-substitutedC₁-C₄ alkyl (meth)acrylate, amino-substituted C₁-C₄ alkyl(meth)acrylamide, allyl alcohol, allyl amine, and mixture thereof. 7.The silicone hydrogel contact lens of claim 6, wherein the partiallyethylenically functionalized polysiloxane is obtained by reacting thefirst ethylenically functionalized vinylic monomer with the functionalpolysiloxane compound at a molar equivalent ratio of from about 70% toabout 90%.
 8. The silicone hydrogel contact lens of claim 7, wherein thepolymerizable composition comprises a bulky hydrophobic vinylic monomerselected from the group consisting ofN-[tris(trimethylsiloxy)silylpropyl]-(meth)acrylamide;N-[tris(dimethylpropylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylphenylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]acrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;3-methacryloxy propylpentamethyldisiloxane;tris(trimethylsilyloxy)silylpropyl methacrylate (TRIS);(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane);(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane;3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)methylsilane;N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silylcarbamate; 3-(trimethylsilyl)propylvinyl carbonate;3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane;3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl vinylcarbonate; trimethylsilylmethyl vinyl carbonate; t-butyl (meth)acrylate,cyclohexylacrylate, isobornyl methacrylate, a polysiloxane-containingvinylic monomer having 3 to 8 silicone atoms, and combinations thereof.9. The silicone hydrogel contact lens of claim 8, wherein the firstreactive functional group, the second reactive functional groups of thefunctional polysiloxane compound, the third reactive functional group ofthe chain transfer agent, and the fourth reactive functional group,independently of each other, are selected from the group consisting ofamino group, hydroxyl group, carboxylic acid group, acid halide groupsof —COX in which X=Cl, Br or I, acid anhydrate group, aldehyde group,azlactone group, isocyanate group, epoxy group, aziridine group, amidegroups, and combinations thereof, provided that one first or fourthreactive functional group can react with one second or third reactivefunctional group in the presence or absence of a coupling agent to forma covalent linkage.
 10. The silicone hydrogel contact lens of claim 9,wherein the first and second ethylenically functionalizing vinylicmonomers independently of each other are selected from the groupconsisting of C₁ to C₆ hydroxylalkyl (meth)acrylate, C₁ to C₆hydroxyalkyl(meth)acrylamide, C₁ to C₆ aminoalkyl (meth)acrylate,allylalcohol, allylamine, C₁ to C₆ aminoalkyl (meth)acrylamide,aziridinyl C₁-C₁₂ alkyl (meth)acrylate (e.g., 2-(1-aziridinyl) ethyl(meth)acrylate, 3-(1-aziridinyl) propyl (meth)acrylate, 4-(1-aziridinyl)butyl (meth)acrylate, 6-(1-aziridinyl) hexyl (meth)acrylate, or8-(1-axiridinyl) octyl (meth)acrylate), glycidyl (meth)acrylate, C₁ toC₆ alkly (meth)acrylic acid, (meth)acrylic acid halide (—COX, X=Cl, Br,or I), C₁ to C₆ isocyanatoalkyl (meth)acrylate,2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-ethyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-butyl-1,3-oxazolin-5-one,2-vinyl-4,4-dibutyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-dodecyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-diphenyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-pentamethylene-1,3-oxazolin-5-one,2-isopropenyl-4,4-tetramethylene -1,3-oxazolin-5-one,2-vinyl-4,4-diethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-nonyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-phenyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-benzyl-1,3-oxazolin-5-one,2-vinyl-4,4-pentamethylene-1,3-oxazolin-5-one, and2-vinyl-4,4-dimethyl-1,3-oxazolin-6-one, with2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one (VDMO),2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one (IPDMO), and combinationsthereof.
 11. The silicone hydrogel contact lens of claim 7, wherein thefunctional polysiloxane compound is defined by formula (1) or (2)FG-G₁-PDMS-G₂-FG  (1)CR(-G₁-PDMS-G₂-FG)_(a1)  (2) in which G₁ and G₂ independent of eachother are a linear or branched C₁-C₁₀ alkylene divalent radical, adivalent radical of

 in which q is an integer of from 1 to 5 and alk and alk′ independent ofeach other is a C₁-C₆ alkylene divalent radical, or a divalent radicalof —R′₁-X₁-E-X₂—R′₂- in which R′₁ and R′₂ independent of each other is alinear or branched C₁-C₁₀ alkylene divalent radical or a divalentradical of

 as defined above, X₁ and X₂ independent of each other are a linkageselected from the group consisting of

 in which R′ is H or C₁-C₈ alkyl, E is an alkyl diradical, a cycloalkyldiradical, an alkylcycloalkyl diradical, an alkylaryl diradical, or anaryl diradical with up to 40 carbon atoms which may have ether, thio, oramine linkages in the main chain; PDMS is a polysiloxane divalentradical of formula (3)

in which ν is 0 or 1, ω is an integer of from 0 to 5, U₁ and U₂independent of each other represent a divalent radical of—R′₁—X₁-E-X₂—R′₂— as defined above or a divalent radical of

 as defined above, D₁, D₂ and D₃ independently of each other are adivalent radical selected from the group consisting of—(CH₂CH₂O)_(t)—CH₂CH₂— in which t is an integer of 3 to 40,—CF₂—(OCF₂)_(a)—(OCF₂CF₂)_(b)—OCF₂— in which a and b independent of eachother is an integer of 0 to 10 provided that a+b is a number in therange of 10 to 30, and a divalent group of formula (4)

in which R₃, R₄, R₅′, R₆, R₇, R₈, R₉ and R₁₀, independently of oneanother, are C₁-C₁₀ alkyl, C₁-C₁₀ aminoalkyl, C₁-C₁₀ hydroxyalkyl,C₁-C₁₀ ether, C₁-C₄ alkyl- or C₁-C₄-alkoxy-substituted phenyl, C₁-C₁₀fluoroalkyl, C₁-C₁₀ fluoroether, C₆-C₁₈ aryl radical,cyano(C₁-C₁₂-alkyl), -alk-(OCH₂CH₂)_(n)—OR₁₁, in which alk is C₁-C₆alkylene divalent radical, R₁₁ is hydrogen or C₁-C₆ alkyl, and n is aninteger of from 1 to 10; m and p independently of each other are aninteger of from 0 to 350 and (m+p) is from 1 to 700, provided that atleast one of D₁, D₂ and D₃ is represented by formula (3); CR is amultivalent organic radical having a valence of a1; a1 is an integer of3, 4 or 5; and FG is selected from the group consisting of amino group,hydroxyl group, carboxylic acid group, acid halide groups of —COX inwhich X=Cl, Br or I, acid anhydrate group, aldehyde group, azlactonegroup, isocyanate group, epoxy group, aziridine group, thiol, and amidegroups.
 12. The silicone hydrogel contact lens of claim 11, wherein thepolymerizable composition comprises a bulky hydrophobic vinylic monomerselected from the group consisting ofN-[tris(trimethylsiloxy)silylpropyl]-(meth)acrylamide;N-[tris(dimethylpropylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylphenylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]acrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;3-methacryloxy propylpentamethyldisiloxane;tris(trimethylsilyloxy)silylpropyl methacrylate (TRIS);(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane);(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane;3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)methylsilane;N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silylcarbamate;3-(trimethylsilyl)propylvinyl carbonate;3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane;3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl vinylcarbonate; trimethylsilylmethyl vinyl carbonate; t-butyl (meth)acrylate,cyclohexylacrylate, isobornyl methacrylate, a polysiloxane-containingvinylic monomer having 3 to 8 silicone atoms, and combinations thereof.13. The silicone hydrogel contact lens of claim 12, wherein the firstreactive functional group, the second reactive functional groups of thefunctional polysiloxane compound, the third reactive functional group ofthe chain transfer agent, and the fourth reactive functional group,independently of each other, are selected from the group consisting ofamino group, hydroxyl group, carboxylic acid group, acid halide groupsof —COX in which X=Cl, Br or I, acid anhydrate group, aldehyde group,azlactone group, isocyanate group, epoxy group, aziridine group, amidegroups, and combinations thereof, provided that one first or fourthreactive functional group can react with one second or third reactivefunctional group in the presence or absence of a coupling agent to forma covalent linkage.
 14. The silicone hydrogel contact lens of claim 13,wherein the first and second ethylenically functionalizing vinylicmonomers independently of each other are selected from the groupconsisting of C₁ to C₆ hydroxylalkyl (meth)acrylate, C₁ to C₆hydroxyalkyl (meth)acrylamide, C₁ to C₆ aminoalkyl (meth)acrylate,allylalcohol, allylamine, C₁ to C₆ aminoalkyl (meth)acrylamide,aziridinyl C₁-C₁₂ alkyl (meth)acrylate (e.g., 2-(1-aziridinyl) ethyl(meth)acrylate, 3-(1-aziridinyl) propyl (meth)acrylate, 4-(1-aziridinyl)butyl (meth)acrylate, 6-(1-aziridinyl) hexyl (meth)acrylate, or8-(1-axiridinyl) octyl (meth)acrylate), glycidyl (meth)acrylate, C₁ toC₆ alkly (meth)acrylic acid, (meth)acrylic acid halide (—COX, X=Cl, Br,or I), C₁ to C₆ isocyanatoalkyl (meth)acrylate,2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-ethyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-butyl-1,3-oxazolin-5-one,2-vinyl-4,4-dibutyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-dodecyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-diphenyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-pentamethylene-1,3-oxazolin-5-one,2-isopropenyl-4,4-tetramethylene-1,3-oxazolin-5-one,2-vinyl-4,4-diethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-nonyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-phenyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-benzyl-1,3-oxazolin-5-one,2-vinyl-4,4-pentamethylene-1,3-oxazolin-5-one, and2-vinyl-4,4-dimethyl-1,3-oxazolin-6-one, with2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one (VDMO),2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one (IPDMO), and combinationsthereof.
 15. The silicone hydrogel contact lens of claim 7, wherein thefirst and second ethylenically-functionalizing vinylic monomers areidentical to each other.
 16. The silicone hydrogel contact lens of claim7, wherein the molar equivalent ratio of the second ethylenicallyfunctionalizing vinylic monomer to the amphiphilic polysiloxanecopolymer is from about 1 to about 1.2.